Heading into tournaments, I have always been asked how it is I prepare – do I play lots of games online? Memorize openings? Study books? Listen to lectures? Ideally, it would be a combination of all of these… but with high school and now college, time hasn’t really allowed for it to happen.
Before anything else, it is important to understand what is one’s stronger points and weaker points – for me, I tend to be easily drawn to very aggressive tactical plans while I have always struggled with positional games where I really shouldn’t even be thinking about sacrificing a piece. Once you know what your weak points are, concentrate on those. Again, for me that would include looking at examples of strategic piece placements as well as learning and grasping a better understanding of my openings (something else I have always struggled with).

Of course, what I have been speaking of so far is the kind of long-term plan that one should always be aiming towards. But what happens if your upcoming tournament is in a few weeks, or even a few days? In such cases, I suggest very strongly that you blitz through as many tactics as you can a day and play blitz games online when possible in order to build your instinct, which will help with analyzing any position you are faced with more quickly in the tournament.
As simple as this may sound, sometimes the deciding factor of who comes out as the victor in a game is who is able to think on their feet better and who is wasting less time simply grasping an understanding of the position.