Use the most popular openings having good engine evaluations.
Victory Percentages of Openings

Assuming people do not always start playing the same moves every time, I cannot always use the same popular openings. Can you name some specifics?

Assuming people do not always start playing the same moves every time, I cannot always use the same popular openings. Can you name some specifics?
Yeah, I even started to write something:
https://www.chess.com/forum/view/chess-openings/beginner-s-guide-to-best-and-most-popular-openings

I think you're going about it wrong, asking which ones are winningest and "moderately aggressive."

By the time you have read all the advice you may be no wiser, because suggestions will all betray our own bias
Anyway. Assuming you have some experience of 1e4 e5 from the black side, I would suggest the Sicilian.But be warned someone will come along and wag their finger at me and so 'oh no, don't take up the Sicilian until you are this or that rating'. In which case you still have to make your choice at some stage. The Sicilian produces interesting chess.
As white you will also meet the Sicilian in my experience 4 times out of 10. Opening Explorer puts 1...e5 as the next biggest reply to 1e4, then 1...e6 and then 1...c6 - the 'big four'. (Personally I seem to have faced the French more than 1...e5).
So as white you will need lines against the three others in the 'big four'.

Thank you all for help thus far!
Urk: obviously getting the "winningest" opening is ideal, but maybe not so for me as everyone is better with different openings. For me, Id love something assertive and solid. Again, not one of the requisites is more valued than any other one.
Ziggy Zugzwang: so it seems like learning the Sicilian is a good idea, in addition to the french. I have played the Ruy Lopez before; is this a solid opening as well?

Well of course yes. I'm actually switching back to 1e4 OTB after a few years away, but for the moment choosing another a less used 1e4e5 opening so as I can concentrate on the other lines. I may decide to look at the Ruy closer later on. The problem with the Ruy is people trot out so many moves without understanding them - which of course could be said of other openings. Then of course you need something against the Philidor,Lativian, Petroff etc as well as defences not included in the 'big four'....
One thing you might consider is adopting a 'world champion' who may play close to what your final repertoire will be and play through his games. 'My Sixty Memorable Games' - Bobby Fischer, who was maybe the greatest 1e4 player of all time. Using a games collection as context for your opening study, in so far as they give you a feel for resultant middle-game positions rather than precise lines. In my opinion trying to rote learn openings is a waste of time.

Thank you Yigor for your chess entry and for your help. These will be very insightful Im sure. What is your opinion on Queens/Kings Gambit?

Understandable, Ziggy Zugzwang. I will absolutely look into Bobby Fischer's games, I hear they are quite the spectacles. Who might be another player to look into when studying d4 openings?

With a view to the black perspective or white or both ? Perhaps a dedicated chess coach may give better advise here than me. The reason I say this is that the older masters such as Capablanca and Alekhine are often suggested for educational purposes because of the clarity of their games, but don't represent modern praxis. So it's a tricky one.
Let me say this. Playing through the games of any world class player and trying to guess their next move; visualising some/most of the variations they give without moving the pieces is guaranteed to improve your game. Like many players growing up in the post Fischer boom we copied his opening repertoire. I recall choosing 1e4 because he played it and tweaked my repertoire as I went along.

I wouldn't care too much about whether an opening scores 54% or 52%...
Most known openings (except those that are bad for obvious reasons) are perfectly playable on the amateur level. I would just try out a few and stick to those that you feel comfortable with.
Also an opening repretoire comes over time, so you don't have to select one before starting to play.

On the white AND black side. Perhaps there isn't one master that sufficiently covers both sides of d4. If not, what two (or more) might you suggest? Alas, a coach is not available to me at my boarding high school, save one with a cost affordable enough. I am less concerned about clarity than the actually learning progression. Theoretically, the more difficult a puzzle, the more information that can be extracted.

Thank you Jengaias!
I see your claim. Though I understand the logic behind your statements, I would restrain from saying they are next to useless. Although numbers are not everything, I would say they are decent results in that they have stood the test of time. That being said, if a given opening did not have at least decent percentages, I would not pick it. That does not necessarily mean I would instantly pick an opening that had superior statistics either. Numbers are not everything, but Im not sure that they are useless.

Thank you Yigor for your chess entry and for your help. These will be very insightful Im sure. What is your opinion on Queens/Kings Gambit?
Queen's Gambit is a solid opening. King's Gambit is tricky and combinatorial. Don't play it unless U know the theory very well or U are able to calculate like an engine.
Hello All,
I am struggling to create my opening repertoire for my first games on chess.com. I will be playing against beginning/intermediate players like myself (1400). Despite using the many resources this site provides (Opening Database, Articles, etc.) I cannot seem to decide which opening is best on either side. I figured that asking more experienced players such as yourselves is my next best option. Obviously I cannot determine what opening will be played in every game, but should that opportunity arise, I need to be prepared to put my best foot forward.
Here is what I am looking for in an opening. Satisfying all criteria is most likely impossible, but the more, the merrier:
-favorable win/draw/loss ratio
-moderately aggressive (playing style)
-often used in grandmaster games
-preferably against/using e4 rather than d4
-select one using black and one using white.
Note: Not any one of these criteria is more important than the others.
Which two openings best suit these criteria?
Any help would be appreciated!