You can leave this out of if you like, but really how many people are going to subscribe when you have a sign up form that just says "Sign up here for our newsletter"?

Well I for one never sign up like that. I get enough emails as it is and I just don't want anymore.

So you offer your subscribers free something to sign up. For example an eBook or maybe a free course.

You can write your own eBook or do a search online for a free eBook with give away rights.

This will be the fastest and easiest way to entice people to sign up.