If you are relying on the pull out method to prevent STD infection or pregnancy you are taking an ENORMOUS risk, but pulling out is still better than not pulling out, however I suggest you and your partner(s) invest in something more substantial.
Pulling out DOES work.
Wrong. It's like basketball: you dribble before you shoot. It only takes one sperm to fertilize an egg or pass on HIV or any number of terrible things. Use a condom.