If you get lots of acne, you should go to your GP, they can recommend you good creams and gels for this. Don't waste your money on things that say it will stop it, its just a way for them to make money.
I used to have very very bad acne for years and spend a lot of money but then I went to my GP and they recommend me to use Zineryt Lotion and Retin-A gel. This really made a huge difference to my skin.
The only downside of the gel is that it peels your skin,heels your skin,this is so you are not left with any skin scars and the infection of the acne will reduce, so use it at night and the next day you have to use a soft cleanser. I would recommend NEUTROGENA VISIBLY CLEAR® Pink Grapefruit Facial Wash, this is great because it does not make your face dry and its a gentle cleanser( removes all make up,very easy). another thing you might want to try and use a natural facial toner, this will tighten your pores and will also have less blackheads. Definitely use a facial exoliator every 2-4 days.
All this products last more than a month.
Your Doctor might also give you some antibiotics, this its just depending on how severe your acne is.