One great way to begin building your opt-in email list is to offer a free download, a free service, a free link, a free article, a free something that would add value to someone joining. But if you give away junk, something that doesn't relate or is just outdated, it will seem more like a bribe just to get people to sign up to your list. That will leave them with a very bad first impression. And that will lead to them leaving. So think about the quality of your giveaway, and if you can make it an article (download/whatever...) that you wrote from scratch, and giving that away as your subscriber bonus, that would be ideal.