If you're not already using them, make sure to test them in some copy. Adespresso recently did a case study on them - conversions boosted 1% and CTR 10% - Great for catching a users eye!
Most used emoji's:
http://emojitracker.com/
Case study on emoj's:
https://adespresso.com/academy/blog/...s-conversions/
Copy / Paste emoji's:
http://getemoji.com/