When collecting information for a newsletter signup or registration form, resist the temptation to try to collect every possible piece of information from a user. Although it seems like this would be the most economical use of a signup form (after all, you have finally gotten the user’s attention), users will get frustrated and fail to complete the form if it is too long; each user is making a mental calculation of how long it will take to complete the form and how much of a hassle it will be.
The aim with a signup form is to collect only the information that will be used for databasing or selling. For instance, if you are never going to send physical mail to your newsletter subscribers, you don’t really need their full addresses; simply asking for their states of residence or zip codes, a single line in the form versus three or four, will give you as granular of location information as you need to run regional promotons while still keeping your signup form as short as possible.
Next time you are making a signup form for a newsletter or your company, try to be as economical as possible and get by with the fewest number of fields necessary. You could start capturing more users with a shortened form.