I wonder which is more responsible for the failure to commit to a move, the fear of heights or the fear of falling. For me, it's the fear of falling and wasting your efforts (the act of falling doesn't scare me at all). Which is why I think it helps to think of the whole route as one big long kickass bouldering problem. Since bouldering is very much about technique and energy-saving, you have to know what position to assume to commit the next move, then be confident and just execute. But the only difference is, there is only one chance. Kinda sucks, but I guess thats the way it works. Meanwhile, dispel all fears of heights and falling. Imagine the mattress is just a metre below you.
Another problem with vertical is not fully utilising the features of the wall as footholds. I think this is a result of a lack of confidence in the foothold. Those tiny spikes or pockets look deceptively slippery, but i guess stepping hard on them when executing the move will help stick it better. And smearing the wall helps when there is no good foothold in sight, and your previous handholds just cannot make it for the next move. But you need plenty of balls la. I need to muster plenty of courage just to dare to smear anything at 10 metres up.
Rest points! Shake out as and when you can, especially when the holds are good and you can find some place to sit in or bridge. Don't tunnel-vision, and keep your mind open while focused at the same time. Slow and steady wins the race. Sometimes, at least.
Practise clipping in. The worse thing to happen up there is being unable to clip in properly, and panic like mad, inducing a sick pump and resulting in a 2-3 clip fall. Enough to make anyone's balls shrink. Find a comfortable position to clip in, rather than hanging on a bad crimp and tiptoe-ing, trying to reach that runner.
That's all I can think of. All these coming from someone who doesn't do vertical much, I hope none of these tips that I came up with from simply thinking and analysing from my bed is crap. Seniors and veterans of vertical comps, please advise! Train hard, train safe!