Since you said you are using a variety of traffic sources (YT, PPV, etc...), I'd start by using a separate TID for each. That way, you can see the different conversion rates for each, and this will give you an insight into which one to focus.
In addition, make sure that what you are saying in your video or ads, matches what visitors see on the vendor's page. For example, if you say that the price of the product is $15 but when they go on the vendor's page it's actually $47, they'll most likely not buy.