Well, there's alot! You can circle PvP, W/Stick tap and more! I'd recommend going into a world and placing zombies (*make sure to active cheats and do /time set night) then, try and time your hits. It's more efficient to hit when the invulnerability wares out. You can also practise with clutching, and bows. But the best practice is to just continuously play the gamemode you enjoy. A good PvP tip to keep in mind however, because of the knockback in Cubecraft, you should try and learn strafing and much and possible. Be unexpected.