The importance of email list cannot be over emphasized.
You might have heard the gurus emphasize that money is in the list,your list is your customer etc.
All they are trying to say is how important list is to your online business.
Email marketing is free but owning a list to send to is what separates success from failure.
Many people use different methods to gather email list but 'profitability' is the name of the game.
Otherwise,what is the essence of email marketing.
In my opinion, the best and most profitable method of building email list is getting people opt in to your list by themselves.
You can do that by setting up a squeeze page and offer something valuable in exchange for their email address.
This could be ebook,software, report or even a free membership to your membership site.
When setting up your squeeze page,remember not to ask too much details as that can scare them off.
You can just ask for first name and email address and promise them that emails are safe as everybody cares for his privacy.
Another way to build a profitable email list is by locking a product and give it a way free.
You can give a giveaway and master resell right to it.
This locked product requires registration the first time it is used in a system.
You send them the unlocking code in their first autoresponder email.
This method make your effort viral.
You can do search on Google for list building software to use.
Email list built with the above methods are very profitable.
They are your subscribers who know you by your name and can't forget easily how they got to your mailing list.
Since you have affected their lives positively, they will looking for a way to pay you back.