Affiliate Marketing Secrets

I’m going to soon launch a niche internet site that will be used as a records management tool. I was thinking of offering a free version with ads and a paid version without ads. From what I gather, that’s how Yahoo works. I could also split the gamut of features offered to allow a basic services package for free and delux services for paid members.
I’d like to keep it as simple as I can, but I’ll need to generate some revenue too…
What do you guys think?