Okay, let's consider that you already know all the theory of this opening. What will you do if your opponent will decide to play c5 or something like that instead of e5? All the theoretical tips related to this opening that you've learnt before will become useless in one moment.
It's not definitely a good deal to rely on such things.
I wouldn't recommend you to study any opening that takes more than two moves, especially if you're not an advanced player. It just doesn't worth its time.
In chess, you must develop your skills in preference to knowledge. That's the only working way to get better at this game.
I have a Highschool chess final vs the best in my school coming up and have been studying the kings gambit. I know my opponent does not study any theory at all but is very good regardless by playing by instinct. Any tips? (I know it is really advanced but I am confident I am up for it)