In the early stages there's various options available to you. It is extremely important that you choose the most suitable style so your document presents as professional as possible. You can select from varying styles including Block Style, Modified Block Style, Semiblock Style. You can have a look at these varying options and select the one that you consider is most suitable.
Buyer accepts offer and signs it, where offer acceptance is binding depends of the legal jurisdiction. For example English and common law differs slightly from American uniform commercial law on matters of offer acceptance and when performance becomes binding on an offer.