Where do you start when you want to run an affiliate program for your product?

Very broad question, but look at affiliate networks such as Impact Radius and find a couple of networks that suit your product area to partner with. Create affiliate materials (ads, banners, email copy, etc). Offer good commission. Keep in touch with top performing affiliates and offer to create bespoke campaign content for them, or ask them how you could help make their sales job easier.

also looking to hear more on this!