If you're using Mastodon through your server's website interface on a computer, there are lots of keyboard shortcuts you can use. Type shift + ? (or just ? depending on your keyboard layout) to see a complete list of all the shortcuts.

You can also type emojis directly in posts by typing a colon : and then a keyword without a space, which brings up the top 5 matching emoji. For example :sun would show emoji with the keyword "sun".

There's more info on these features at https://fedi.tips/using-mastodon-through-a-keyboard/