There are various ways to make inserting emojis easier.
You can pull up the emoji keyboard by hitting ^+⌘+space
Right click on your taskbar and enable "show touch keyboard button". Click on the keyboard that is next to your taskbar clock. Click on the smile face to find and insert emoji.
Install package for autocomplete-emojis.
Atom can also help with using emoji in commit message by installing git-plus
Install package for GithubEmoji.
Create an .npmrc file and set the message value.
message = ":bookmark: %s"Not currently available. Vote for this issue to ask for it.