Also worth noting that very often as melee it's better not to run out too far. In most cases you can even stay on the edge of the bosses hitbox and barely move at all. Let the ranged run away from you and spread a little from your fellow melee/tank.

Not only is this far better for uptime (which is vital for melee dps), but too often I see melee running halfway across the arena chasing the ranged with aoe markers. It's unnecessary but easy to do if you're new and panic.