[s_e_s]

there are a few things you have to remeber before becoming an affiliate:
1. shipping methods of the company (if it takes up to 1 month, then it's not your choice )
2. reputation and experience of the company
3. what kind of products they sell (generics, brand name drugs etc.)
4. company's licence etc.
but, in general, that a good way of doing affiliate business.
there is another niche that's quite profitable, it's stocks analysis and things like that.