For one thing, if all of the basics are not there, then you do not have a usable bill of sale template. Even if it is free of charge, avoid any template that does not indicate a place to write or type the names of the buyer and seller, along with their addresses and telephone numbers. If also there is a place in the template to include e-mail addresses, that is even better.
A Bill of Sale acts as a receipt for both parties. The seller can use it to prove that an item was sold to the purchaser "as-is", and the buyer can use it to prove that payment in full was given to the seller. It also provides a sale date to both parties, which can show when the responsibility of the item was transferred. Both the purchaser and the seller can use it as evidence of the price paid for tax purposes.
This is especially true for the buyer, as it is usually the seller who has composed the bill of sale (or hired someone else to compose it). Therefore, while both the buyer and the seller must consider the terms of the sale very carefully, it is especially important for the buyer to understand the legal considerations of the bill of sale.
Free bill of sale forms are offered on this page. A bill of sale is a legal document made by a seller to a purchaser, reporting that on a specific date, at a specific locality, and for a particular sum of money or other "value received", the seller sold to the purchaser a specific item of personal, or parcel of real, property of which he had lawful possession.