Listen to PODCAST by the Millionaire Blogger
Here is a link to the show notes post with 7 incredible examples of high converting email opt-in forms used by pro bloggers and instructions on how to set up these different forms on your own blog.
https://theblogmillionaire.com/160
http://theblogmillionaire.thebloggingmillionaire.libsynpro.com/5-highest-converting-email-opt-in-forms