You want to have a professional, or someone who knows what he or she is doing. In internet marketing, income, proof and experience beats everything. So when you want to buy an e-book and not just collect free digital dust anymore, you'll want to seek professional tips and tricks.
Tip 2 out of 5: Proof
Proof... Oh man, this is a biggie for anyone who is a bit seasoned in the game, but when you are a "newbie" it's not easy to recognize "truth" from "fiction". Some people make outrageous income claims which nobody who has been around would believe... But when you are starting out, it's not uncommon to fall for these types of "emotional triggers", I know I did when I was new.
Tip 3 out of 5: Credibility
Who is the author? Does he or she have more than one website or a blog? Does it have a newsletter? Can you Google him/her and find multiple articles or websites created by the same person? Does he/she have more products in the same topic and can you find them? If they do it's usually a good indicator that they for a fact are credible and know their stuff.
If you want even more credibility, look for testimonials. If the website has nice testimonials from solid people or websites it's fair to say it's credible. Are the testimonials video or audio? If some of these things are true then you are looking at someone who is backed by a good crowd.
Tip 4 out of 5: Design of Website
A professionally designed website with a header graphic that feels professional is a great sign of a solid website. You should reconsider if the site looks like it's created by a 10 year old.
Tip 5 out of 5: Are other people are recommending the product on review sites or similar?
This means that if you search for things like "review" or "testimonial" or "success story" on Google you find at least one or two website that have a solid review of the product. This is VERY common and should indicate a serious business owner who has gone great lengths to find affiliates and joint venture partners.