Lead the enemy into your shots.
Skial
Chance
Chance
Works better with Scout/Engi/or the shotgun with them other classes
Ninja Scout
http://forums.steampowered.com/forums/showthread.php?t=2032578 Talks some information on mouse sensitivity but explains the best TF2 training map that you can configure yourself.
Zefyre
in console exec aimbot.exe works every time
Avenger
stand still when you take shots, nobody will ever hit you if you stand still
Pinker-tan
use your mouse