Mail to your list immediately! As soon as you have one subscriber send out an email. The email can be as simple asd a than you for subscribing.
Offer something for free. A freebie is an item that you will give away to people who fill in their name and email address to get on your list.
Send your list something of value; like I am doing here. I am offering tips on building your list.
If you don’t know what your customers want then ask them. Find out what problem you can solve.
Keep in constant contact with your list. You should email your list as often as you deem appropriate.