What this does is it keeps on bugging them to join until they do join and then it stops. Always have at least one pre-sell and post-sell list for your membership site. When creating the follow-ups for your pre-sell lists, and these are more reasons to deliver it every few days to purchase, just look at your sales letter.
Look at the reasons you give for somebody to join your membership site. Look at the problems you lay out and how you solve those problems. Look at the common objections people usually have for membership sites and how your sales letter resolves email list them. Your email sequence is just your sales letter cut up into little tiny pieces. You should have at least 10 follow-ups sent out every single day to your prospects.
If you need more than that, then add more at the end, send out every few weeks, and then every few months, just to make sure that people are reminded even weeks or months later, why it's important that they join. Then, add your post-sell lists and all you need to do is simply tell them upfront what to look forward to, what's coming, and then send one message per week telling them what they missed or participated in that week and then a link back to the blog where they can log in and consume more of the content.