Email Subscriber list not growing anymore

[batman]

Email Subscribers are not like getting traffic. They may happen a lot in a day and into another none. Stay clam and just like 'Batman' said attach the banner of yours in every page of your site. You can also use a popup in your homepage. But remember popup should be just shown once otherwise it will be too annoying to the visitors.

Yeah, I agree you can create a pop up too. But just don't make it lousy. You can also insert the subscription link in your content text. It will be clever too.