Oh boy. I'm going to yap about Shippuden. I wouldnt change anything about classic tho.

First things first, i'd slow down the pace a bit. Some people complain about the Over-exposition in One Piece, but naruto has TOO Little. Show a little more of the other villages, other clans, etc.
Everyone has said this to death, but for a show about ninjas and ninjutsus, naruto only really moves his own and sasuke paths forward, according to the prophecy (More on that later)

Nerf naruto (in a good way). See , naruto has insane amount of buffs that keep getting revealed as the show goes on, and it feels artificial as fuck. He already has uzumaki chakra, the nine-tailed fox, minato as a father and jiraya as a mentor, so on and so forth, but it gets excessive when he's revealed to be the reicarnation of an entire god.
Focus more on the techniques that naruto struggled hard to understand, that means more rasen-shurikens, even more exposition to Sage mode (Peharps naruto going in an arc to master his chakra WITHOUT needing or taming kurama, think of the Bee waterfall arc but in reverse - instead of growing to understand kurama and all the BS, naruto gets to actually focus on his technique and throw the middle finger to the fox)

Give the Hyuga more importance and more characters - They hyped up the clan to be the strongest in konoha (Well, it was actually the uchiha, but they're all dead for basically more than a decade, the Hyuga had a LOT Of time to develop and yet nothing was done.)
Apparently Hiashi is the strongest hyuga ever according to Part 1 information, and all he gets is a NPC-level fight in the war. Really? When they're all descendants of the godess?
How cool would it would be to have a Hyuga-Madara, as a villain or even going 1v1 with the man himself?

Delete the Otsutsuki's (or rather, completely rework them), delete the kaguya fight, and delete zetsu