Spend on the essentials
Training - buy the ranks you use. Leave unused upgrades for a later visit.
Mount at 40 - plan for 100 gold at level 40 starting around level 20. Keep the mount fund separate from unused spell ranks.
Consumables - health potions and food belong in the route budget.
Gear - use Auction House greens at weapon breakpoints and stamina upgrades. Replace a slot when the upgrade solves a specific gap.
Earn along the route
Vendor items the character does not need. Grey items help pay for a potion stack.
Skinning, Mining, and Herbalism add gold while you follow the normal route.
Auction House flipping uses deposits and can leave gold tied up in unsold items. Keep enough liquid gold for training and supplies.
Avoid expensive habits
Buying every trainer rank. Read the upgrade and delay ranks that do not change the active bar.
Skipping the mount for a small gear upgrade. The mount saves travel time and shortens long route segments.
Saving gold by skipping health potions. Keep a potion budget before buying optional gear.
Keep a reserve
Keep enough gold for the next training visit, consumable refill, and route-changing purchase. A reserve gives the character more options.