Sometime when you are sending out a professional letter, you need to make sure that it is written on the right type of paper. If you send it on paper that is thin, or colored, it sends the wrong message for a professional letter. Paper for business letters should be on a standard white/ivory/cream and should possibly have texture and some thickness to it. If it is written from a company, it is also a good idea to have some kind of a watermark seal or stamp on the paper itself. If all of these things are followed, it will make a good impression.