The best way to advertise PPC on Google Adwords.

I don't use Adwords much. But I was wondering if using the search network and/or content network is worth it. I ask because when I click everything I've discovered my ads on some crappy sites and, while I get lots of clicks, they don't convert. I'm thinking that if click fraud exists --- and I'm sure it does --- it would be worse on people's sites.

So my question is, what should I click to get get the most for my money?