My first tournament was at the rec center in college. I wasn't very good but luckily nobody else was either
I played the best I had played to that point and managed to win $20. I don't even remember if that was first place money or second place. I remember that it was $20 because it was enough for a sixpack and a pizza...In those days.
Then later I started playing bar tournaments and even though I played (made balls + position) about as good as the better players it took me a long time to figure out how to win and then once I did I won a lot of bar tournaments. I went two and out a lot. I lost matches to people I wasn't supposed to lose to. I did all the wrong things. It was tough for a while.
The thing is, playing tournaments is just practicing playing tournaments. You have to adjust your game a little and find what works for you. The biggest thing is not to get discouraged. Everybody loses, everybody wins. No big deal. Nobody but you will remember how you did unless you win.
Before I started winning I got second place a lot. Lost the finals. I probably lost the finals 5 times before I won. It's easy to start thinking that you just don't have it. You just can't win. etc... I did that after a couple but then I realized I was practicing winning the tournament and the more times I put myself in the finals the more practice I would get and the better I would get at winning.
And sure enough, I broke through and won. And then I won again, and again. Pretty soon I was the player everyone hated to play in the finals because I almost always won if I got to the finals.