I thought I posted here, but maybe I didn't send it.
For a quick pimple fix (won't prevent them, but will reduce them overnight) try a product called "X-Zit." For me, it works better than peroxide or other salicylic acid products that I've tried. It also isn't expensive and you can order it online. Covering pimples is always going to be a challenge.
I've used MAC for years. It is by far the best make-up I've found to cover up blemishes. They have a product called Studio Fix. Applly it with a big blush brush, not the sponge they give you. The first time I went to a MAC store, the clerk was a male crossdresser. I was sold. In all seriousness, for a man to look like a woman, they've got to be able to cover up their beard - it takes a good make-up to do that. I also find it to be one of few make ups that doesn't make blemishes worse.
Before my wedding, I went to MAC consultation. The clerk was fantastic! She picked out great colors, and showed me how to apply them. On my wedding day, I was able to do my make-up myself. Everyone raved about my make up! Even withou an appointment, if you go at a less busy time, the clerks will usually spend at least a few minutes helping you pick the right colors. I've found MAC store employees to be more helpful than some of the department store MAC sellers, but that is just me.
I rarely try other products, but I have tried a few Bare Minerals products and they seem to be pretty good too.
It is also important to keep your make up brushes clean, and to replace your make -up every so often if you aren't using it up quickly. The less you touch your face, the better.