How to prepare for an specific opponent?

Study his facebook profile extensively and find out what he likes most. Then as the game drags on and he grows weary, you pop out the mother of all whoopie pies, or whatever, and devour it greedily. Boom! Instant checkmate!

In the case he prepared as well, it's best to offer a draw and propose a trade.

I like your points there Diakonia! Very interesting, the psychological aspect of chess has always captivated me.

I only know my opponent is a dentist. I think I will try coming to the game with bad breath. 

The simple answer: You don't need to prepare, and will not have to, for a long long time.

(1) It's hard to know specific opponents at your level - below the master level, there are very few games of your opponent you can find online, which are the only reliable sources of info for you.

(2) Below the master level, the objective evaluation on the board is the most important thing by far. Masters try to prepare against specific opponents' weaknesses because they are so good at the game, that they need this advantage to win. You definitely don't - you just need to exploit your opponent's inevitable tactical mistakes.

(3) This is different from preparing *for the game*. I believe that, if you want, you can prepare some lines that you will play in certain openings, but this is different from preparing for a specific opponent. 

I usually look at some games 1 or 2 days before my game to look at middlegame ideas. 

The idea of spending all day in the lab looking at his games sounded cool to me but I dont have the data or the need right now (according to chess.com forums).

Thanks for your comment.

In the game you posted - I can tell you some weaknesses right away:

*Your opponent has some holes in his/her positional understanding - playing moves like ...Be6, for instance, when white gains a tempo for his/her plan (which white didn't know about - white should've tried to advance on the kingside). by playing Ng5, and can follow with f4. I also don't agree with ...c4 move, because it makes black's queenside play weaker. 

*Your opponent makes tactical mistakes, but is generally tactically competent - he/she lost material and got a worse position, but white not only simplified into an equal endgame, but even lost by making another blunder.

The unfortunate thing is that white, in this game, cooperated with black, and didn't try to advance his/her plan. We see the most mistakes of players when both sides are making challenging moves against one another, and that wasn't necessarily the case here, for white.

I was looking for an answer to the same question and found an old article on chess.com by WGM Natalia Pogonina (she's one of the regular members of Russian Olympic chess team) 
Thought it could help, too https://www.chess.com/article/view/preparing-for-a-game

The Best ways to prepare for a particular opponent are: - 1) If you have lost against him earlier be confident, nobody knows when game changes 2) Study the opening he/she plays. Try to go throw different games played on same opening and lines. 3) Analyse the game,to learn from your mistakes. Thanks!! Don't forget to send me a friend request if you agree with me, if you don't reply to my comment.