It depends what your goals are bro.
Do you want to try and completely shutdown your oil-glands? If so, you would have to run accutane @ 60 - 80mg/ed for 4 - 5 months (obviously ramping it up though over the first month or so..)
^^ I know a lot of fellow BB who have taken this route, and swear by it.
If it's just to get rid of acne for now (keeping in mind that when you go on your next cycle and you aren't on the accutane you will break out again)... then I would suggest running it @ 20mg/ed for 4-5 months. (or until all the acne is gone.)
This stuff is strong, has sides, and is definitely crazy effective.
If you're acne prone (which clearly you must be..) then you should follow the acctuane dosing regiment I previously suggested in your next cycle. it will make a world of difference bro!
Hope that helps..
-VM