If you have experience, with clickbank affiliate marketing, which kind of products, would you recommend to market! On the basis of popularity,gravity,some particular niche or something else?
Either promote something which is currently hot (check out www.cb-analytics.com) or promote something in the market that you know well.
Niche products that haven't been hyped up are a good bet. Some simple research will tell you if it's worth promoting.
Depends on your strategy and your skill set. If you just want make a quick buck with a thin affiliate site and promote through PPC or crappy SEO efforts then choosing a less popular niche would be to your advantage. You'll have a much easier time ranking for keywords. However, it will likely be less profitable. If you want to focus on more long term income then chose a wider niche and promote more popular products. However, I'd advise staying away from the Make Money Online niches.
I've had greater success in promoting niche products compared to high gravity products (like Fatloss4idiots - haven't made a single sale on this).
Ya, I guess I would start with niche products! Ya, I know Make money niche is a big NO NO, if you are just starting off!