As I look at a route I am about to try. I think that I can do this, and try to feel confident in myself. This usually includes me looking at every hold and physically moving my arms in the position I will grab the hold. Next I will try to find every taped hold I see to make sure I am not missing any moves. Next I will chalk up and say to myself that I can do this. Then finally hop on the route!
There is always mistakes that can be made but after your first attempt it is always a great idea to go over the movements. And think what else you could try. Usually when you fall it is because you did the wrong beta therefore-- it might be a good idea to try a different way.
When I try a route more then 4 times I ask myself if I am still physiqued about the route or not. This is very important to ask yourself because if you are not physiqued about the route then its not worth your energy.