0. Build a growth plan with a coach like me
1. No one mentioned the most important tool - email.
2. Create a regular posting schedule and stick to it
3. Split test your signup forms
4. Get referrals using something like Rafflecopter

Get an email list started with Mailchimp or Sendgrid or GetResponse. Offer these educators something of value and get them on your list. Social media followers are a good complimentary to email. Give them a reason to join your email list.

This is truly how top bloggers build audiences (some also make social media work) -- surprised it was not first on everyone's list.