I played about 12 years in a club and participated in a lot of youth tournaments. Right before I started studying at university I stopped playing chess. Now after nearly 5 years I recently started playing a few Blitz games here. I noted some players who wonder how to improve in chess and I thought I can help out here a bit. The following notes might be helpful for players up to a rating of approx. 1700 or perhaps even higher. In a case of reading the whole article please give me a short feedback, thx.
If you loose often: I'm pretty sure the majority of players here plays in a club or at least played in a club once. Do not be so hard on yourself! In a club or in tournaments improving at chess is generally easier. But of course it's possible to improve at chess without joining a club. If you want to improve, I have a few recommendations for you:
1.) Blitz is for fun, it is not real chess. The extreme time limit is just an excuse to make bad moves. I like playing Blitz a lot, but you can't improve your chess this way. So play longer games! Think a few minutes before each move. One game in a typical tournament lasts 5, 6 or even 7 hours. Typical time limits are 2h/40+1h/20+0.5h/rest, so that you have 2 hours for your first 40 moves and your opponent as well, altogether up to 4 hours for the first 40 moves. It doesn't have to be that long, but even 30 minutes each is called rapid chess. So try to play games that last 2 hours or longer. When thinking let's say 3 min before every move (in average), you can get a better feeling which pieces are defending each other, which squares are weak, what are general plans, and so on. It can be in the internet or, even better, on a real chess board.
2.) Analyze those long games after you finished them. This is an important one. It is not just about understanding your faults, but also about different variations you might have thought of during the game, but which you didn't play. You can use software like Fritz, but it is better to take a real chess board again. Analyzing Blitz games is normally not productive.
3.) Ask stronger players to analyze one of your games. For them it won't take that much time and they can tell you 3 or 4 critical positions in which you/your opponent blundered or made a bad exchange, started out with a bad plan, ... This is of course easier done in clubs or in tournaments. Often directly after a game players analyze their games. Once I played vs an IM (rating 2400) in a tournament (I have about 2000 in real chess) and according to him the game was about equal in the first 37 moves, but then I kinda blundered and he won easily with technique. The best thing ever was analyzing the game with him afterwards. I was really impressed by all what I had not seen during the game and learned a lot!
4.) Chess is often divided into the phases opening, middlegame and endgame. Also there is positional play and tactical play. At a level general positional factors and basic principles. Especially those are hard to learn by yourself. But here stronger players or good books can help.
I will give you some basic ideas:
This would be a dream position for white, and for black it's the same mirrored. The two knights not at the edge, the king is safely castled and perhaps most important of all you control the center with your d- and e-pawns. You have more space and can easier operate, e.g. you could consider attacking at the king side or at the queen side. Hence, it is not surprising that most openings won't allow the opponent to reach such a position. Even in the Pirc defense 1.e4 d6 2.d4 Sf6 black only allows white to control the center temporarily. He wants to castle and enforce e5 or c5 later. Whether the bishops are better at the squares c4/f4, d3/e3 of course depends on the position.
This might be too easy for you, but I comment it: This position is horrible for white. He made a lot positional blunders: Knights are in general bad at the edge because they have less controlled squares and are not operating in the center. The brave pawn at h5 is just a huge weakness if you want to castle kingside later on. Rooks are developed after the minor pieces. You can easily loose them and they are more valuable than knights and bishops (5>3), they are a lot of stronger later if they occupy open files or of course in the end game. The doubled pawn without side pawns is perhaps worse than one pawn. This is not that easy to see, but in the long run (maybe not untill end game arises) they can easily be attacked e.g. by rooks but they can't easily be defended, especially not by pawns.
In closed positions like this (pawns blocking each other), knights are generally considered to be stronger than bishops. The e2 and e7 bishops can become strong, but white's bishop at d2 and black's bishop at e6 are basically "big pawns". White, who has less space, would like to open the position a bit by playing c4, also freeing his d2-bishop, and in best case exchange it with it's stronger counter part at e7. This would garant him a positional advantage at long sight.
In open positions (with some middle pawns exchanged), where minor pieces can act freely, bishops are considered to be a bit stronger than knights, especially the bishop pair (maintaining the 2 bishops while your opponent doesn't) can be huge.
While at this chess server I am recently noticing a trend towards later castling, you normally should castle early and after it finish your development. Your king is simply safer.
Typical middlegame plans include: doubling rooks on open files, pawn breaks, attacking at the kings-/queenside, exchanging bad pieces, winning space by pushing pawns forward (the drawback is: later they can easier be attacked by your opponent), open lines and active piece play (this is hard to describe, maybe a general feeling; get pieces at strong squares where they have a lot of possibilities to move or limitate the opponent or where they support each other...), attacking weaknesses of your opponent, the minority attack (in case you don't know it, simply google it), knight manoveurs towards good squares, ...
In order to understand and find out more general positional factors, maybe the best way is talking to stronger players or reading special chess literature.
If you want to play some theoretical lines, on the part of many GMs it is recommended, at least untill a level of 1600/1700, to start with open variations 1.e4 e5 (and there for white rather the Giuoco Piano (Italian Game) than the Ruy Lopez (Spanish opening)) or semi-open variations with a good reputation, especially the sicilian defense 1.e4 c5. You simply get a better feeling of your minor pieces in open positions. I am just thinking about most club players below level 1500 don't do so, but play minor lines. At least this is my impression. Maybe they want to surprise their opponents. This can be effective in some games, but they likely miss a bunch of plans arising in the "good" openings.
5.) Tactics/forced moves are important, but not that important as most beginners think. No pc in near future can calculate every variation untill the end of the game because there are too many of them (it would be the dead of chess btw). Therefore general plans are important! Whatever, in some positions you have to decide whether sacrificing a piece helps to mate the enemy's king or winning the queen a few moves later, or you simply see an enemy piece that seems to be defended, but it is not really due to several reasons...
Tactics can be improved by solving mate problems/winning move problems. Hard ones with a lot of time and easy ones in few time (take a look at http://chess.emrald.net/ for the latter case). Maybe playing Blitz does also provide a bit of help in this department.
And of course calculate possible variations in long games. For beginners it is generally easier to calculate forced lines in a position instead of finding "silent moves" (I don't know how it is called in English, it is a move that appears normal, without any direct threats, but that actually is very strong, e.g. reaching some zugzwang type of position).
6.) Study endgames! This of course can be somewhat boring, but it helps. Not all games are decided by a direct mate attack in the first 20 moves and the point is that you get a better feeling which positions to strive for, even a long time before the endgame arises! It is a good feeling to enter an endgame with equal material, where you know you have way better chances to win.
Start with: mating with queen, mating with rook, mating with 2 bishops, [bishop+knight is tricky and you won't need it that soon; 2 knights is almost always a draw], queen vs rook, queen vs 7th rank opponent's pawn (result depends on kings distances to the pawn and on the pawn's file, but in most cases there is a winning technique), pawn endgames (I find them very exciting and beautiful ). The rest, especially rook endgames (rook + pawns vs rook + pawns), is more complicated (for grandmasters too) and maybe not that important at a stage below 1800.
7.) Further advanced techniques include: playing special opening lines you normally don't play (in some clubs there are little opening tournaments where all have to start from a given position), blindfold chess (good for improving your memory), playing through games/ watch games of stronger players, ...
Chess is not much about intelligence. It is about recognizing patterns that offer you an advantage or simply recalling how to act in special patterns. You learn more patterns, if you play more long games and think deeper. But just playing the same f*** as always obviously won't improve your play. At least in this department chess is a real sport. Compare it to swimming. If you swim every day 30 minutes, this alone won't guarantee a swimming skill improvement or speed improvement. It is a question of technique.
Hope some has been helpful. If you enjoy playing chess, your chess will improve all by itself!