Chessplayers have different values and tastes about different openings. One likes to play solid Caro Kann, the other one rather plays crazy gambits or sharp Najdorf. There are also different ways to play the openings phase: play what you like or follow common theory. Nevertheless I think it's important to see the difference what someone likes in chess with what is beneficial for him and improves his skills. Often people like to defend their pet opening. I have studied openings around 20 years because I have enjoyed it. Whether you like or not studying opening theory there are anyway few things that
opening phase can teach you. The most important thing is NOT are you able to remember 30 moves of certain Najdorf line but openings, beneficial openings, teach positional things for you. They improve your skills. All this asks that you have to be active. Simply remembering lines without understand the basic ideas behind of them leads nowhere.
Opening phase and opening theory is different for titled players and nontitled
First of all, let's mention the most important difference. We can't imitate playing style of Carlsen, he is top level player and we are not. We neither are able to imitate his opening play. Yes we can choose the same opening and variation, line, but the rest is just someting very different.
Top level players have to work a lot with openings and find out the new lines that are played. This is because top level players don't make many mistakes in the game. If Kramnik gives slight advantage for Anand and they are equally prepared on the position it's very difficult for Kramnik to win the game. Top players are often able to use that slight advantage they have got from opening and give a lot of pressure with it and convert the advantage to victory.
There is practical choice for us to make: whether we want to follow and try the lines Kramnik plays and use a lot of our time or do we want to improve our skills on chess. If you are a player for example under 1800 there is no need to study many openings. For example 1800 rated players do more mistakes than 2000 players and that's why practically it is minor problem whether 1800 player gets even position out of opening as black or gives slight advantage for his opponent who is playing white. It is beneficial for player
to know theory as much as average same level opponent does. Naturally average 1800 player knows less theory than does 2800. For 1800 it is more difficult than 2000 to use the bad untheoretical move opponent has done and convert it to win. Please don't get me wrong: I don't mean to mock 1800 rated players or anyone. I am mostly talking about practical consequences. 1800 is already experienced player and he is able to win many his opponents
and is of course likely to use blunder of his opponent.
These are only some examples that makes opening theory different for let's say 2800 rated and 1800 players. The further you are from 2800 level the bigger difference there is.
Speaking about myself, I am around 2300 rated player, also far from being top 2800. Still players around 2300 don't make many mistakes and that is the reason I have to focus on openings clearly more when I was 2000 rated.
Another quite totally different aspect about opening theory is that some openings seem to be even on top level or at least give a lot of draws for black while the same thing doesn't happen for rest of us mortals. One example is Petrov defence. It is drawing opening for top level and it seems to be quite equal. Nevertheless on my level players doesn't seem to have the right technique to force white to take draw and also Petrov seems to offer slight advantage for white.
The openings you should try as black
There are many beneficial openings for you to choose from. I call them beneficial openings because there is no need to criticize anyone playing e.g. some wild gambit Kramnik or Carlsen would never play. Everyone have right to play chess how he likes to and that makes this game even more fun and interesting!
Here is some list of openings that are beneficial:
-Queen's gambit Accepted =
-Caro Kann =
-Najdorf = (and many other sicilians as well)
-Queen's gambit Decline
First mentioned openings with = mark are very even openings that offer very equal chances for both sides. The rest 4 openings are also practically good but people have to be more careful using them the more nearer they get on titled level. For example for other FM I would mostly suggest using even openings as black. They are good tools for him use when he occasionally plays against strong opponents like GMs.
One opening is very good with great statistics but practically bit problematic on tournament play: Grunfeld defence. It consists lot of theory and it is also one of the difficult openings I know. I used to play it for awhile but stop it because of huge amount of theory black needs to know.
Openings for white
Naturally there is more freedom on opening phase for white to maintain at least even position. I myself sometimes just throw 1.b3 as white to tease my opponent with boring opening. I think white should maintain at least even position on opening phase and not play too strange lines. Mostly I recommend following similar principles I have mentioned above also playing as white. There is at least good opportunity to learn many things about your own opening if you choose more common openings and lines also as white. You
have a chance not just read strategical points and analysis by GMs but also follow their games.
Why these certain openings are beneficial?
I start from unbeneficial openings. Yes you have right to play them if you want. Nevertheless if you want to improve in chess they block your improvement and even make harm on your playing style. It's not only about matter of taste what opening you play because you learn different things on different openings. Many gambits teach harmful things about neglecting material due to short-term tactical possibilities. Nevertheless the higher you get on rating the more you see that you opponents master the defence better than you expect. This means that the tactical possibilities are reduces after some moves and then you are left nothing but material disadvantage which unfortunately lead in lost position.
Here are 2 different openings:
If you compare these 2 positions you see that they are quite similar with only tiny differences! One important difference is that on english black has even material but on Budapest white is pawn up. English is even while logically Budapest with about similar position but pawn less on black's side can't be even.
Lot of players are fascinated by sharp attacks but the sad story is that if you
concentrate a lot in sacrifices and attacks you don't see all the other things player need to learn. Beneficial openings teach a lot of crucial things about positional things and different pawn structures. Here are some to just name a few:
-French: teaches about pawn chains and proper wing attacks. Both players often attack on the root of pawn chain and mobilize the pieces on the side with space advantage. Black often has space advantage on queen side, white has on king side. Black often attacks on white's d4 square for example Nb8-Nc6, Ng8-Ne7-Nf5, Qd8-Qb6, Bc8-Bg4 (to trade bishop to Nf3 that defends d4 pawn.).
-Najdorf: teaches the value of weak squares (d5 for black), blockades (d6-d5 can't be moved easily) and tactical skills. White's piece mobility is maybe slightly tiny than black has. As compensation for white he has strong control of d5 square and black has weak backward pawn on d6 that is luckily well defended early. Anyway these kind of weaknesses black has on this opening are sometimes problematic for black side if the game goes to endgame. Often also on endgame, not just on middlegame, black has enough play on
c-line, queen side and pressuring e4 pawn.
How many openings it's necessary to study and learn?
The more further you are from top level the less openings you need to study and master.
This is based on few things:
-You do more mistakes so naturally it doesn't matter so much is the starting point - after opening is over - slight advantage for your opponent or equal position.
-Your opponents on average haven't studied many openings
-There is no point to use thousands of hours on opening theory simply because there are lot of other things to learn as well! Endgame techniques, positional things (pawn chains, wing attacks, minority attacks...etc)
As for example 1500 rated player it's ok if you always play french as black against 1.e4. As 2000 it would be good to probably have that same French as part of main opening repertoire but also sometimes play something else against 1.e4 let's say Caro.
As a hint on studying new openings: many openings form a family with at least bit similar set ups and strategics. Caro, Scandinavian and Alekhine all has solid pawn formations on black side with often strategy to challenge white's pawn center with c5 or e5 advance. On these openings black mostly focuses on piece play and less on pawn advances. Black doesn't have many pawn structure weaknesses but he rather uses weaknesses of white side. This is of course typical when opponent has space advantage. New opening from same family is easier to learn: If you are used to Caro you may understand and learn Scandinavian incredible well compared if you start to study something completely different like Najdorf.
How the opening study should be done practically
The good way to start studying opening or deepen your understanding the opening you have already played is of course buy proper opening book that consists many strategical expalanation about at least mainvariations and the ideas. Opening book that consists only strings of moves is not enough good because you need to learn the ideas behind the moves.
Video lectures by titled players are also very good to at least scratch the surface.
Be precise to try the ideas you have learned on games. Generally one of the hardest things on chess is the problem of how to convert the raw theoretical knowledge as better skill that helps you to win games! This is especially important on opening and endgame, but also on middlegame. After you have played few games of French but somehow lost without idea why this have happened get back on the source where you studied some french
and check and compare what mistakes you did.
Study some classical or other top level games of the opening you use. On what kind of middlegames they go? How they handle different kinds of weaknesses and strategics when moving from opening to middlegame and endgame?
If you have database of master games please use it to consider whether some line is playable or not.
Use the engine to check the tactics of positions after opening phase and also check engine evaluations if some odd and uncommon position occurs. Just remember that weaker engines don't understand openings very well and always the theory should be primarily and not engine's ideas. Nevertheless I have seen that Houdini 1.5 and newer versions already
understand openings quite well they very rarely make mistakes.
Focus on beneficial openings, but those with less theory
I think it's important to start focus on beneficial openings but choose variations and lines, even openings, based on the fact "The less theory, the better"-principle. This may sound absurd because often the best variations and lines from black's perspective consists tons of theory. I think some cross point should be searched for.
There is one example. I used to play Grunfeld as black with bit bad results and I also had problems with the huge amoint of theory it consists. And all that theory, well, there is a lot of it! Then I just decided to try QGA as black with very good results and less theory knowledge. I even managed to win IM as black although some friends of mine warned that you can't win higher rated opponents with it as black! They are maybe partly right, but at least once I did win. Still now I feel and think that QGA is much practical opening than Grunfeld, but this is mostly my own taste.