One of the biggest mistakes that people make with lists is that they fail to really get to KNOW their subscribers. They may think they know them, and they may know *some* things about them ... but, oftentimes that's not enough.
If you really want to get the most clicks and the most sales, then you simply must know what your audience really wants.
When was the last time you polled your list?
Seriously, When was the last time you asked them their opinion?
Do you realize the enormous value in asking your list members for their wants, ideas, feedback, suggestions, needs, etc?
When they give it to you, they have just handed you a list of things they are interested in buying.
If they think "generating traffic" is the most important thing to them, then you hunt down traffic generation products and services to offer them.
If they hate the way you do some particular thing, then you stop doing it.