What you need for the fight, depends on your minecraft game level

Weak-ish: Prot 4, Sharp 3-5, Bows Power 4-5, Infinity and you need a shield and a good pickaxe and alot of blocks/ladders, and gapples and str 2 pots

Average: Prot 2-3 ,Sharp 2-3, Bows power 3-4, infinity, shield, decentpickaxe(eff 4 dia or smth), blocks/ladders, long str 1 pots, half a stack of gaps

Better than Average: Prot 1 works, Sharp 2, Power 2. infinity, a decent pickace, blocks/ladders, short str 1 pots, half a stack of gaps

TryHard: normal dia gear, normal sword, infinity bow, normal dia pick, blocks/ladders, a water bucket, some gaps

Whichever suits you, you can use

You should have feather falling, protection, thorns, fire aspect, mending, and sharpness at least. Remember that potion effects and fire cannot be applied to the dragon, so don't bring spectral or tipped arrows. Flame bow is also not needed. You can't shoot Endermen nor apply fire to the dragon, but bringing a bow in general is a good idea.

Gold is better man. You probably don't know, but golden armor actually gives you a regen buff. You don't notice it, but trust me, it helps. Also, the ender dragons weakness is snowballs. It takes twice as much damage as an arrow, kind of like the way blazes do.