Step-By-Step -->
1. Find Your Affiliate Program
2. Build A Landing Page
a. Make A Review Of the Product
b. Compare With Other Products Why The Product Is The Best Choice
c. Make sure the linkings in the page are easy to be clicked!
3. Do some article marketing / Direct Linking PPC
a. Link to your landing page which has reviews on the product
b. Get your readers interested in the product (why should they buy it compared to others)
4. Test your ads
a. See which ones are reaching to more people
b. MORE IMPORTANT: see which one which converts better
c. EVEN MORE IMPORTANT: If you're using ppc, MAKE SURE your keywords are relevant.
Just my 2 cents