I study the resulting pawn structures and plans. That way, if my opponent makes an out of book move, it usually means that I can implement my plan much more effectively i.e. exploiting weak squares, pawns etc.
Learning new openings

I go through interesting GM-games with engine, trying my variation, why something doesn't fit there and so getting the picture of the opening, pawns' position and so on.

@LaskerFan - I do browse various lines sporadically to try and get a clue, but you're right - I usually don't want to work hard esp in the opening so I guess my first "fix" should be to cut my gameload down to a handful of games instead of a dozen or more so I can put more effort into fewer games

I go through interesting GM-games with engine, trying my variation, why something doesn't fit there and so getting the picture of the opening, pawns' position and so on.
I used to do this a lot and now I have too much of a tendency to make 'computer' moves. I play something insanely complicated when I only partially understand the position, because I can sense what houdini would do. This is responsible for quite a few of my losses, even though I was usually right about the move being good according to houdini.
Thanks, nice tip. I think I also do too much comp moves, so from time to time I try to play openings which are "bad" for computer...

My opinion is that using a db to study a new opening is a wrong way. DB doesn't teach you why a move is good, it just gives you the stats of the moves played.
I learn from books.
So you've got a book for every single opening you play and the ones your opponents force you into playing?
BTW DBs don't "just give you the stats of the moves played" they give you the entire games as well, which can be organized by players ratings, the move order played, the dates the games were played or the game results

Buying anymore chess books is no longer an option for me; I've got way too many now that I'll probably never get around to reading this lifespan. Hopefully the Hindus are right about reincarnation, maybe I'll get to read at least some of them next time around?
BUT I agree owning books such as "Play the (whatever) Defense" or "Learn the (whatever) Opening" is a really good idea - IF you've got time to read them! AND I've also noticed since such books are not encyclopedic as a rule my opponents occasionally "wander off the beaten track" and play moves/variations not covered in the books at all.

My real hobby is playing through games collections. I enjoy the various styles of different GM's from the past. My openings choices are a result of various favorite games that I have come across in my readings.......as white a Queens Gambit...as black...vs 1e4 French or Alekhine...vs 1d4 Dutch Leningrad.......

My real hobby is playing through games collections. I enjoy the various styles of different GM's from the past. My openings choices are a result of various favorite games that I have come across in my readings.......as white a Queens Gambit...as black...vs 1e4 French or Alekhine...vs 1d4 Dutch Leningrad.......
I get my opening ideas the same way. And I enjoy replaying the games of my favorite grandmasters.

Chess engines are horrible in (1) openings - position is too complicated for proper eveluation (2) endgames - with only upto 6-piece tablebases out there the engines can be easily defeated in complicated endgames (3) closed positions where strategy is more important than tactics. IMO people who heavily rely on chess engines for guidance do not develop beyond a certain level.
I doubt it. For the endgame, and closed positions, fine.
But for openings? No way!
Haven't you noticed all the stunning piece sac novelties were analyzed with and probably suggested by a computer? Also, they have rehabilitated some offbeat lines, which used to be considered bad, but now are deemed respectable.
Of course, they are only good in some types of openings, such as lets say Najdorf, or tactical openings in general. In closed systems, they are less helpful.

Books and DB.
Normally I try coming up with a convincing answer to my opponents possible openings. For example-
As BLACK I need to prepare facing 1.e4 1.d4 .c4
1.e4:
If I respond to 1.e4 with 1..e5 I need to be prepared for 2.Nf3 2.d4
to 2..Nf3 I need to prepare at least one good response, and the same about 2.d4 I have to have one good response. So vs 2.Nf3 I'll play 2..Nc6 heading into either the Ruy Lopez or the Italian Game, both which I know very well. And vs 2.d4 I''l play 2.exd4 knowing i'm ready to face 2..Qxd4? 2..Nf6 and 3..c3 .

You need to grasp the basic ideas of your opening (either by yourself, or with another player familiar with the set-up or with guidance from books/articles).
Then go for a bunch of annotated games for some middlegame ideas. "Bunch" could be as little as one or as much as 20-25, depending on your level of play and preparation.
Then play in quick games, analyze and learn.
That's the amateur way, and I think it works fine...
How do you guys/gals learn/study new openings?
I usually just follow out lines from my DB and try to go with moves I'd play anyway (unless they seem to be real clunkers) or else the most commonly played move in most cases, to try and play the most typical positions in the opening or variation. I also try looking up a typical line in MCO-15 if it's in there; I usually don't have the time or ambition to play thru a bunch of games (annotated or not) with the line although I will look thru specialized opening books if I have any on the particular line.
Lately I've also been organizing thematic tnmts with openings or variations I'd like to learn, which I think is handy because I'm rarely opposed to playing something I'm interested in as White or Black.
Any other thoughts here?