You want to segment your subscriber list based on shared needs so that your subscribers respond similarly to your marketing strategy.   Ineffectiveness arises in email marketing when you do not address your subscribers’ needs or your subscribers become disenchanted with your products or services. Effective email marketing involves developing a relationship with your subscribers that is built around addressing their needs.  Through list segmentation you are able to differentiate between the different needs of your subscribers so that you can then send targeted mailings that your subscribers will respond to in a similar way.  Send messages that are irrelevant to your subscribers’ needs and you risk losing them.  The better you are able to segment your lists the higher your response rate.  Treat your subscribers as if you were in a relationship with them and they will respond to you more.  List segmentation should not be rigid or fixed.  If you are responsive to your subscribers they will be responsive to you. How you segment your subscribers will change over time as you learn more about them.
Sending out email surveys are a good way of collecting additional information about your subscribers.   This information can be used in addition to your subscriber fields to put you in a better position to segment your subscribers.  When using subscription forms you should only ask for critical information.  If you make your subscription form too long you may be creating a barrier for people that would otherwise be interested in signing up to your list.
Including a short survey link in an autoresponder you send out after a subscriber joins your list is a great way of collecting non critical information that can be used to more effectively segment your list. You do not need to ask your subscribers everything you ever wanted to know about them in one survey either.   A short questionnaire with only one or two relevant questions can be very effective.  Your subscriber will be more willing to participate especially if you explain to them that you are asking these questions so that you can send them information that is more relevant to them.  You can then send them more short surveys from time to time in order to collect additional information so that you can continuously segment your subscribers.
Another option would be to send out a survey when a subscriber purchases a product from your website.  You can use this survey to gather preference or opinion data that can be used to better segment your subscriber list.   You can learn how they feel about a particular brand or technology.  These are meaningful segments that allow you to send more relevant messages.   Are your subscribers brand loyal or do they look for the best deal irrespective of brand.    Are they purchasing a camera because they are a photographer or is it only out of necessity for a special occasion?  You can set this up by redirecting your subscriber to a page containing a survey embedded in an iframe after they purchase a product.
You are asking your subscribers about their needs, preferences, and behavioral patterns as part of your market research.   Your survey should ask questions related to the marketplace and an industry rather than focusing on a business.   This information is a good predictor of your subscribers’ future behavior and will form the basis of how they are segmented for truly targeted email marketing.