Best herbs to be growing early-mid game? (early Dungeon farming)

Just killed Skeletron. Dungeon is certainly a "step up" in terms of difficulty. I think I need to start crafting some night vision potions (at least until I can get torches established).

-- side note, how rare is the Water Bolt, is it guaranteed to be in the dungeon? --

In researching night vision potions, I realized there are many other helpful buff potions. What are some "basic" seeds I should be keeping an eye out for, for the most beneficial early potions? I don't want to overburden myself with farming right now, really only looking for 2-3, maybe 4 potions to upkeep while in the Dungeon. Likely a utility like night vision, maybe a damage and maybe a defense.

If my gear matters, I have the Crimson(for lack of proper name) armor set that gives regen. The sword and bow from it. I have a decent gun and a really bad magic weapon (part of reason I'm farming Dungeon).