The Number one Flaw in Affiliate Marketing

A major flaw in your quest for Affiliate marketing is Concentration on Sales.
Yes, the primary purpose of affiliate marketing is to generate revenue, at least for the marketers. That much is self-evident. But you should never be too concerned with "selling."

Instead, you should concentrate on assisting others. Whatever happens,
You should be concentrating on aiding your market in some way, because this is how you add value to your affiliate offerings and increase your revenue thus stimulating your market's audience to believe in you and want to buy from you.

Your basic purpose, regardless of your market, is to assist others, help them with required information and knowledge.

Literally, when you help them loose weight, you're assisting them in getting in shape and staying healthy.

If it is Internet Promotion, You're assisting folks in making money and achieving their goals.

Therefore, always focus on rendering help to your market audience, try as much as possible to satisfy their desire to know more about the niche area for which you cover.