Convincing a visitor that you are the right choice for them is always hard for the first sale.
Start the sales letter explaining to them that usually what they would be reading now is all the reasons why they should buy. This, however, is different. You want to play a game with them.
You will give them a headline that encompasses all you would say in one long sentence, and put in it all the benefits, features, etc. that are important for you to convey.
You then list for them all the standard points you were going to make a list of short, concise titles. Things like benefits, features, objections, etc. They now have to click on each of these titles one after the other. When they click a title, they will get a pop up with a list relevant to that title (features for a beauty product: not animal tests, shining skin, takes only one minute to apply, etc.) mixing in also such features that are not related. The game is for them to click on the right features only. They do this for all titles.
This way they – and not you – are expressing all the important points you want to make.
You then give them a score, show them the points they missed, and can even give them a reward (maybe a sliding discount dependent on how few they missed – they might even reload the page to get a better score the second time which will only enforce all the point again in their mind), or ask them for their email to send them their scores