You will want as much information as you can get from those signing on to your email marketing lists in order give you a chance of targeting the first few emails. Your email marketing software will give you much more detailed, and precise, data later but research suggests that the first 30 days gives the best returns from each individual subscriber. So the obvious answer is to oblige each new subscriber to go through a plethora of questions before you allow them on to your email lists.
There is a catch. There always is. Most people do not like sharing their personal information. It is hard enough getting their email address let alone their age and where they live. Further, and probably more important, many people are confused by forms. Your preferred format is unlikely to be the same as that of other companies. The lack of a standard set of questions is one that is likely to plague the procedure for some time to come.
There is no guide that can be precise and say ask this question but not that one. What information you want will not necessarily be the same as even that of your rivals. If you have counters across the country you might want to know where those on your email lists live so as to be able to identify their nearest shop. Others might be more international and all that is required is their country of origin.
You must therefore pick your questions with care. Ask yourself if that extra box to complete is worth the risk of them jumping ship.
One way of getting people to cooperate is to tell them why you want the extra detail. Explain that it would mean the offers would be more likely to interest them. A bit of honesty never goes amiss.
Explain that you will ensure their details do not go to anyone else and give a link to your privacy statement. Make the mandatory fields obvious and validate the email address. Consider doing it with the postcode if that is important to you.
Above all, make it easy to complete. A little frustration and the back button might be clicked.