Advanced Leveling Guide For Next Character

You will need to transfer all items from an established character via Shared Stash.
Do 1st main quest on Normal to unlock Shared Stash.
Equip all XP gear Grim Tools[www.grimtools.com].
Use Potion of Clarity[www.grimtools.com].
Do quick side quests in town on Normal.
Use Savior's Merit sold by Marr in Conclave of the Three to unlock Ultimate.
Use all Mandates[www.grimdawn.com].
Use any Warrants[grimdawn.fandom.com] you may have.

Use Imbued Silver[www.grimtools.com] and Purified Salt[www.grimtools.com] on Weapons and Off-Hands.

Do 1st Main Quest and quick sides in town on Elite.
Run single rounds in The Crucible for next 4 Devotion Points.
Run Shrines and unlock Factions by completing Main Quests on Normal Difficulty.

Purchase low level Augments with resistances like Rifthound Salts[www.grimtools.com] and Slith Venom[www.grimtools.com] when available from Faction Vendors.
Kill mobs with stars and Totems along the way for Faction Rep

Run remaining Shrines on Elite optional.

You will be over level 50. First chance run 1 to 2 SR on Ultimate to level 85 then enjoy the campaign.
The reason for unlocking Factions on Normal is to have full rep when reached on Ultimate.
The reason for lvl 85 ASAP is so good drops have a chance to be lvl 94 and useful long term.
Alternatively you can tag along in a multiplayer SR to level 94 if you have ALL the XP gear as a respect to other players. I recommend level 94 with full build to quickly run campaign for required rep and fun.