First, cleanse your face.
I use Neutrogena Skin ID but you can use whatever you use.
Now, before you apply any make up, make sure your pimple(s) aren't bleeding or open or anything. If they are, you need to dry them out first, with rose water or tea tree oil, something like that.
If you apply make up with open pimples (pimples that have busted open and what not), you are spreading the bacteria all over the face, increasing your chances of more pimples.
Apply foundation where you need to the most first, and then where you don't need it as much.
I focused where most of my blemishes and where my redness was.
The key to this process is dabbing, so dab and pat the foundation in instead for a more even coverage.
Dab it around the pimple, especially where it casts a shadow if it's a bump.
Then, powder. Translucent works the best, though, I suppose pressed would work also.
Look how clearly reduced the pimples are.
Here's the final product, with eyeliner, blush and so on.