Showering post workout, don't scrub them hard! Change your bedsheets regularly and drink plenty of water.
Believe it or not try head & shoulders shampoo on your back/shoulders. Its extremely cheap & effective.
Also try & avoid touching your face and effective areas as much as possible.
Hope this helps. Seriously don't waste your time buying expensive acne creams & such, give head and shoulders a try, it can be found for as cheap as £1 a big bottle.