1. Create a unique selling proposition (USP).
Developing a USP for your ezine will make your ezine more attractive to your niche audience and help your ezine to stand apart from other competing ezines.
Comprise your USP from a single, compelling benefit that people will get from subscribing to your ezine.
Your benefit should be something that only your ezine offers or that other competing ezines fail to stress in their promotions.
Once you've created your USP, integrate it into all of your promotions for your ezine.
2. Swap ads with other ezine publishers.
You could swap sponsor, feature, classified or solo ads with other ezine publishers.
Choose related but non competing ezines to swap ads with and track your ad swaps so that you'll know exactly which ezines are best to continue swapping with.
3. Swap "thank you" page ads with other ezine publishers.
Advertise other ezines on page your new subscribers are taken to after joining your ezine in exchange for those publishers doing same for you.
This will give you very strong promotion of your ezine for as long as other ezines continue to be published.
4. Write articles.
Your articles will help you to successfully increase your subscriptions by getting your ezine promoted in relevant ezines and on high traffic sites.
Promote your articles by submitting them to article directories, article announcement lists and also to other ezine publishers.
5. Swap articles with other ezine publishers.
You could run another publisher's article in your ezine in exchange for her publishing your article in her ezine.