Cost per action/sale methods require that referred visitors do more than visit the advertiser's website before the affiliate receives a commission. The advertiser must convert that visitor first. It is in the best interest of the affiliate to send the most closely targeted traffic to the advertiser as possible to increase the chance of a conversion. The risk and loss are shared between the affiliate and the advertiser.
Provide the most accurate information about the products you promote. Never exaggerate to quickly make a sale. Your audience will see through it and they will turn their backs on you. Instead, if the product you are promoting isn’t perfect, say so! It never hurts to explain the downsides to a product because this just proves to your audience that you are being completely honest with them. Also–this is very important–be transparent about your relationship with the merchant! It is legally required that you disclose your affiliate relationship, so any time you share an affiliate link you need to let your audience know. Make sure you are following the latest FTC guidelines here.
I would like to add that for information products, a lot of the time it’s pretty easy to rank for “information product review”. I recently did a review of a popular ebook that is a month long discipline program. I went about it by doing the actual program and documenting everything. At the end of the month I wrote up a 2700 word article summing up the whole experience.