I always find comps are an exercise in management of resources; skin, enurance level and time.
I have the third round of a comp series at one of my local walls coming up on Saturday. I've learned from the first two rounds that it's a lot about tactics on the day.
The series I'm doing is unlimited time & attempts during the day, so endurance and time are basically the same thing for me: I find I can't (try to) boulder hard for more than three hours tops, no matter how conscientious I am about trying to rest & recover enough between attempts. And in the series I'm doing, worked harder probs score more than flashed easier probs, so it's about trying to balance flashing everything I think I should be able to, whilst still having enough in the tank for decent attempts on some harder things. And knowing when to cut losses when something turns out to be hopeless: it's a comp not a training session.
Skin: comp problems tend to be on new resin holds, so very abrasive. I tape up, lightly and loosely, at the start to preserve skin, and only take it off if I have to because it's getting in the way. Also foot endurance: as Richie says, take some comfy shoes and do as much as possible in them before resorting to your best bouldering toe cripplers.
Take plenty to drink and some light energy snacks: bananas, fruit bars etc.
And watch carefully. At my wall they always set some trick problems aimed at weeding out the merely strong: precarious foot traverses w/no handholds; finishes that involve lying down on volumes to reach finishing holds below & to the side; finishing hold round an arete where reaching over the top is much easier than round the side. This kind of thing can be eminently doable once you've seen the trick, but confusing & error prone if you try to onsight them.
