Well, congrats on making it to the 2nd boss; it's not so easy with a vanilla Huntress. Even harder with item degradation.
The Huntress is all about her ranged attack. You want to keep as much distance as possible between you and the mobs. And keep upgrading that boomerang.
Use the Huntress's ESP to your advantage to detect enemies before they see you. Open doors with thrown items and use skill shots to hit mobs around corners. (Go ahead and read the rest of that guide too; it's mainly for the Sniper subclass, but there's lots of good advice, though some of it is outdated).
As the Darkoko notes, you want to ask the wandmaker for a non-battle wand. Hopefully you get Slow or Blink, either of which will make your life easier. Of course, if you're playing the latest version of vanilla PD, item degradation will soon make your wand nearly useless unless you keep upgrading it, which... sucks. So yeah, good luck with that.
Use your boomerang to kill piranhas, and save your invisibility potions for bosses. Unless you're playing the latest version of Shattered, missile attacks don't break invisibility, so you can snipe away with impunity and 100% accuracy. Even without invisibility, Tengu will be your easiest boss fight: just stand on an earthroot plant and trade shots with him until he dies.
I haven't actually played a whole game with a Huntress since the last update, so I don't know how much harder it is, but I suspect a lot. On the other hand, bees and bombs are probably pretty helpful.
By the time you reach Tengu, your chosen weapon should be dealing at least 15 Damage. [i.e. +1 Longsword; +2 Battle Axe; +3 Sword; +4 Mace; +5/+4 Knuckleduster]
By the time you reach Tengu, your armor should be absorbing at least 16 Damage. [i.e. +1 Plate Armor; +2 Scale Armor; +3 Mail Armor]
I put both melee & ranged, since you're just a Base Huntress, so you can play either way; only the Sniper sub-class requires focusing on Ranged combat. The main thing is Debuff Application Management; if you can stay on top of that, then you're golden.
Make Missile Weapons your bestfriend! Especially Curaré Darts, Incendiary Darts, & Tomahawks! Also, Bombs & Golden Bees!
Take full advantage of your Sensory perk!
Swarm of Flies - Make sure you farm Health potions from every Swarm of Flies you encounter.
Gnoll Shaman - Farm scrolls from them, but make sure you never engage them at long range. If one sees you from far away, either close the gap immediately (if you're able to), or make it lose sight of you & wait until it catches up to you - always fight it through melee, never ranged.
Skeleton - Avoid these guys whenever possible; if you're forced to fight one, make sure you use ranged attacks only (opposite of the Gnoll Shaman).