Your Opponent Actually Thinks!
We all know what a fork is, yes? It's a popular tactic - the concept of attacking two enemy pieces at once with a piece that cannot be immediately taken. For example:
Puzzles surrounding forks (and other tactics as well) are way common. "Find the Fork" puzzles are fun, usually not too difficult, and are good exercises.
But these one itty bitty thing - when you're actually playing a game with someone, they are looking for these tactics too! So while you think you might be playing a good game, suddenly, seemingly out of the blue, your opponent forks your queen and king and you'll have to say a surprised goodbye to your most powerful piece. Who would have thought your opponent actually knows about the same tactics you do? Go figure!
Things like this can usually be easily remedied with an extra thought process when planning your next move. By considering the position from your opponent's view, you might just be rewarded with some extra insight into his Grand Master Plan (no pun intended), and with a little move, you could thwart it altogether, ideally putting yourself in a good attacking position at the same time.
This doesn't apply just to forks. Pins, skewers, removing defences, everything. Of course you're looking for them, sure. Keep on truckin' with that. But also take some time and look at the position as if you were your opponent. You'd be surprised just how much like you they really are.