I’m a fan of this particular call to action (example from Amit Shekhar):

Thanks for reading this article. Be sure to click ❤ below to recommend this article if you found it helpful. It means a lot to me.

It’s honestly telling the reader what the recommendations mean to you, and it’s a cool use of the ❤ emoji.

Also, it trains any non-expert readers in how to use this Medium feature — important for example, if they’re coming from your mailing list, Google, Twitter, Facebook, instant messaging, etc.