First and foremost, you should always be washing your face. Cleanser or exfoliators are great! Just your normal skincare routine would be good! There's tons of products but I'm not going to get into all those today.
My holy grail! Tea Tree Oil is a natural anti bacterial so with acne you have on the skin caused by outer things it works great! You simply just apply the oil onto a Q tip and directly on the skin. It won't go right away but it does work!
I great trick to use when you are trying to get rid of a pimple or prevent it is to steam your face. You can easily just run your tap until it gets hot and soak a face cloth in the water then hold it over your face. I don't know what it is about it but it always works.
Sleeping on those pillows every night, you are bound to get some build up of dirt and bacteria, which will transfer on the skin causing breakouts.
One thing you shouldn't do if you want to prevent pimples is touch your face. Your hands have so many germs all over them from throughout the day and by touching your face you are putting all those germs on your face which will lead to them getting into your pores, causing breakouts.
How do you prevent pimples?