do what ever you can do as many times as you can do it. If you can go across both wakes, do it. It you can do a surface 180, do that too. If you can do a wake 2 wake heel side but not toe side then just do that. Do as many different things as you can in the time allowed. I am a beginner adult who competes and this is what I do: I do surface 180's as the boat is still getting up to speed. They are easier to do slow. then I go out toeside and come across one wake then the other, just to warm up and feel out the wake. Then I cut out and do a wake 2 wake HS. Then I do some lip slides and turn 180 over the lip. Then I cut out toe side switch and do a half cab which puts me back regular. Then I go out heelside and cut back in for a one wake 180. If I am still going I do a couple more heel side wake 2 wake jumps and head for a slider and try to go up it. If you can only cross the wake then do that as much as possible. What I have found the comps do for me is get me to get focused and prepare quickly. I never win, but I ALWAYS have a great time and push myself to do the tricks and focus with very little warm up.
Good luck and HAVE FUN