Let be the first to officially welcome FM NFork from Finland to chess.com (Hopefully, his title will be attached to his name promptly). :) Listen to what he says folks, he is very talented!
Play with 2 colors
So in other words, think about what your opponent might do, something you should be doing anyway?
What is meant by playing with 2 colours?

I believe what NFork means is to not only plan how to manuever your forces, but consider the plan and ideas of your opponent. In other words, pretend you're playing both sides and assess the chances from there...

Thanks aww-rats, yes I mostly meant what you said :) Even if you have white pieces try to forget that and think of the moves from the side that has turn to move. Play like you were analysing the game as it was a game of 2 other players. This is mostly good advice if you miss lot of tactics from your opponent's side.
This is simple advice, but I think playing with 2 colors is good idea in chess. Don't stick up to play too much on your own pieces. I sometimes use even 50% of my time forming plans for my opponent! This way its easier to avoid getting carried away with attacks that opponent can defend well. Lower rated players also too often seek aggressive attacks, because sometimes the best move is to stop the plan of your opponent.