Boss potions are most useful when they address a specific weakness. You do not need every available buff for every encounter.
Survivability first
If attempts end because you are taking too much damage, prioritize defensive or regeneration-oriented buffs before stacking more offense.
Damage buffs
Once survival is stable, offensive buffs can shorten the fight and reduce the number of dangerous mechanics you need to survive.
Mobility and utility
Some fights are lost because movement or resource management breaks down. Treat those buffs as core preparation when the encounter demands them.
Class-specific planning
Melee, ranged, magic and summon builds can value different combat buffs. Match consumables to the class and weapon you are actually using.
Keep the loadout sustainable
Farm ingredients for the few potions you use repeatedly. A small reliable stock is more practical than crafting a huge one-time list before every boss.
Use the boss guide to choose
Open the individual boss page first, identify the problem, then return to potion planning. This keeps preparation focused.
Source: Official Terraria Wiki — Potions.