An excellent thread is currently underway at SEO Chat forums on the topic of how to find and manage those cream of the crop affiliates of yours.
People discuss that they like to focus their energy on their 'top affiliates.' The classification of 'top affiliates' range from 95% of your revenue is 5% of your affiliates to 80% of your revenue is 20% of your affiliates. Which one is for you? The 95/5, the 90/10, 85/15 or the 80/20 ratio?
The thread also gets into how some recruit affiliates:
1. Direct emails to top ranking high quality sites 2. Referrals from existing affiliates 3. PPC ads on PPC engines 4. Participation on the forums 5. Recently an Ad in Revenue Magazine 6. Affiliate Dirrectories 7. Partnerships with other non-competing affiliate programs