In reply to HenryJM:
make sure you do different sets, alot of the time its your triceps that need to be worked so move you closer together, but to make sure your body is balance have some distance in them as well. i prefer to do 5 sets of 20 with each set being different.
have you thumbs and first finger tips touching so there is a diamond shape made under your chest.
have you hands under your shoulders with your elbows next to your sides.
normal position.
then 2 more sets getting wider apart
start of with lower reps until you become comfortable with doing so many.
bp