Jim Edwards http://www.thejimedwardsmethod.com and Stew Smith discuss many of the external obstacles you will face when trying out and testing new sales copy.
Let the market tell you if your sales copy is working by testing segments of your products and audience / membership lists. Build a successful strategy to creating the best methods that work. You will not know they work until they are tested.
Try a few options per product you sell and see if the eyeballs viewing your site and pulling the trigger to purchase (or not).
This month's challenge - test out new sales copy on a product of your choice.
Sales Copywriting and Content Marketing Hacks Podcast with Jim Edwards