There are a lot of good tips from the other guys here, it is important to use a good quality ammo, i use winchesters in my semi-auto as they seem consistent and kill well as they seem to mushroom on impact a good way to check bullet drop is to shoot in to a dry sand bank as you get instant feedback and know where the bullet is going, as for tips i usually find that with a semi you should be able to get 2-3 shots so start high then work down, experience will slowly show you this, most importantly you gun must be zeroed, try using a black and decker workmate to lock the gun in place, i found this useful when starting out
all the best
DM