Well its quite common problems peoples are facing.If you take care of these problems in a proper way you will feel more confortable.Both the prevention and medications will take some time weeks to months to show the result.Its not like the ads you see on TV, cure acne in 2-3 days or something.
Oiliness gives undesirable look and is also major cause of pimples,folliculitis and a type of ezema known as seborrhoeic dermatitis.First you should take care of oily skin.
Either avoid or use less oily creams,when necessary choose a lotion/milk form.Wash frequestly but gently with small amount of normal soap (which doesnot contain glycerine)or face wash (5.5 PH),twice ot thrice daily,Washing only with water will not remove the oily secretion.
Reducing oiliness will gradually reduce pimples also.Don't squeeze pimples,which gradually cause inflammation and later leaves scar.Let them dry gradually,it will take some more time.
The treatment mainly consist of antibiotics,Vitamins A derivatives and hormones.Treatment for pimples is long,at least 5-6 months and to see some results it will take 2-3 months.
It will be better if you once again follow a course of appropriate treatment under dermatological consultation.
Remember acne is a age related skin condition and usually goes at around 25+ of age,and i have found many girls acne or pimples are gone after marriage for which hormonal changes play role.Medications only control acne and does not really cure it.