Bring a bow with plenty of arrows
Bring a strong sword
Bring a pickaxe
Bring blocks for climbing and bridging
Bring water buckets
Bring food
Bring a pumpkin if you want to avoid endermen aggression
Wear good armor
Destroy the end crystals on the obsidian pillars
Use a bow to shoot crystals you can reach
Build up to the taller pillars and break the crystals by hand
Avoid looking at endermen
Use water to reduce fall damage and repel endermen
Attack the dragon when it perches on the portal
Hit the dragon’s head or body with your sword during perches
Shoot the dragon with arrows when it is flying
Keep moving to avoid dragon breath and knockback
Heal up when needed
Finish off the dragon after all crystals are destroyed and its health is low