how to get better armour

im still in leather

 

You'll find new armor over time in loot chests or you can buy them from merchants and the trade market.

Also the material type is not important, the armor stats are.

 

I'm never going to let go of the fact that Wynncraft does a god-awful job at translating this to earlygame players

Caves are the standard way for you to obtain new gear and weapons to upgrade your setups. Take your content book, sort by "Caves" and filter by "Closest Level". Run the few that are listed and you'll be set in no time. Be sure to do this whenever you feel like you are short on power across the entire game.