Sales letter and copy of some kind is used over the entire internet to sell the literal millions of different products and services. So, in order to write successful sales copy, you'll need to learn about the many types of mistakes that are made, so you can avoid them.

A simple mistake made by many copywriters is that they don't know the core details about the product they're promoting. If you don't understand the product you are writing about you aren't going to be able to convince someone to buy it. Your prospect could easily figure out that you do not know very much about the product. This will take a major toll on your conversion rate and lower your sales. Never forget that you need to know everything there is to know about the product you are selling--the good and the bad. Once you know the product completely you will be able to use creativity to illustrate the better points. When you are sure about your subject it is easier to communicate about it to the prospect and make sure they get the right impression. Do not make the mistake of giving away too much for free to the client but still try to get all of the required information out there. If you don't know how to balance your information this can be tricky. You want to educate the potential buyer but at the same time your sales letter needs to create the urge to buy. The easiest way to do this is to play up the benefits of the product so that your customer knows just how it will benefit her. Don't go too heavy on specific features or the other details won't really matter when it comes time for the customer to buy. Keep your sales copy fluff free and make sure that the necessary details that will make the customer buy are included. Plenty of copywriters forget that their copy is not for them but for other people--customers specifically. Focus on the potential customers you want to attract instead and then target your sales copy to them directly.

Also, you really do need to be careful about editing and fixing any grammar or spelling errors. It's just a fact of business that people will judge you, and if they think you don't have it together then they won't buy from you. So that's why proof reading and revision were invented, and they can make all the difference sometimes. If your prospects get a feel that you haven't taken your sales copy seriously, then they'll obviously feel that your product isn't that worth it. So just make sure you can read through it several times while checking for different kinds of errors. If you avoid the mistakes we've talked about, your copywriting should do its job nicely.