too many marketers don't focus on list building and frankly, too many have no clue what it is. list building is basically the concept of building a list of contacts that agree to accept solicitations from you.
email listbuilding has been proven to be a very productive, relatively simple and fast way to generate leads, referrals, sales, and commissions for many marketers and is a technique used by all serious marketers.
typically, listbuilding and advertising go hand in hand which means that it is likely going to cost money to build a good quality and sized list, with the idea that the list will pay a return in the form of sales and commissions.
once you are earning a return from your list building efforts, it becomes easy to put more money into growing your list, which in turn means you should earn even more, and the cycle continues. this is why having a recurring commission type offer is especially beneficial.
the key is to track and test your conversion rates while you advertise. create a high converting funnel to get the most bang for your ads.