Do not wash your face more than twice a day, and when you do, make sure you use a gentle clenser such as cetaphil :)

But it will also expose softer skin that infects more easily, so more acne.

Whenever you wash your face, it obviously removes all of the dirt and oil on the surface. Washing your face too often will result to really dry skin. In addition to that, the sebaceous gland produces more oil to compensate. More oil = more acne.

stop drinking soda and eating chips

Drink things that are anti oxidants they do wonders for skin and so does drinking water.
You need a cleanser that cleans your skin but doesn't completely strip all your natural oils from the skin. People make the huge mistake of thinking stripping all the oil from the skin will help.
Try not to touch your face too much, your hands can make your skin dirtier without realising.
Try find products with salicylic acid in as it's brilliant for oily skin and spots. Origins is a good company to go to for products, it's all natural and they put a lot of research into skincare.

The best thing for acne I've found in my case anyway is Witch hazel and Green tea. I have sensitive skin so I can't use Clean and Clear or Clearasil. You can drink green tea and apply it externally, it also helps reduce redness. Always make sure to apply moisturiser afterwards as if your skin is too dry, your skin will over compensate for it's lack of oil and then you'll end up with more pimples.

Junk food doesn't cause acne or pimples either but it does help if you have a healthy diet.