The first thing you need to do with this answer is to make your choice about which topic you will choose to write about. For example, as yoiur quewstion is about business, you could imagine you are trying to convince a Human Resources department in a big multi-national company to buy your marvellous hot-selling book or course literature about driving sales up or increasing recruitment. Then go back and build in the methods outlined for setting out your ideas. Remember there are many techniques used in persuasive writing that can enhance effect and buying signals from the recipient. For example consider persuading the audience/reader of the benefits, then use a 'call to action' - persuasive text encourages readers to do something.
For example, think of the letter as an advert - an advertisemnt persuades people to buy something. If you write it as a report then a persuasive report would sway readers to believe a viewpoint. Persuasive texts use repeated words so use this technique to drive home your point. Also consider using text in capital letters or use suggestive techniques such as rhetorical questions (ones that do not need an answer.) Present a one-sided argument that is hard to find fault with and the letter readers will feel they are on your side. There are many ideas but first you must choose your medium.