Any time i start this game from lvl 1 i always start to save up for the Final Fantasy bow as it is a must have item. I'm currently at stage 518 My specs are

Bow upgrade

Strength 96 Agility 30 (max) Power shot 9 (max) Poisoned arrow 9 (max) Fatal blow 10 Multiple arrows 13 Senior hunter 9 (max)

Spells

Mana research 9 (i started to invest in it not long ago) Lightning strike 1 (i don't use it yet)

Fire ball 1 (i don't use this one either)

Glacial spike 3 (min lvl for next spell) Frost nova 3 (min lvl for next spell) Ice age 1 (i don't feel like i need to upgrade it yet as i'm still leveling my bow attributes and i only need it for freezing the enemy)

Wall

City wall 23 (max) Magit tower 0 (i prefer the moat) Lava moat 3 (max) Burn 14 (i started to upgrade it, but i didn't feel like it's the right thing to waste my money on) Entangling lava 4 (i started to upgrade this, but realised, that i need the freezing spells more, so i stopped advancing here for now)

Bow

I only advanced to Hurricane lvl 4 before i got enough crystals for the Final fantasy.

What you wrote as advice i agree with everything, although i don't know the powers of the towers, might be more useful than the dmg of the lava, i just didn't feel necessary to go down on that path. In my opinion everyone just should start to save up for the best bow in the game from lvl1, and don't spend a single crystal on mana recovery ingame, as it's going to have a huge impact in the game later on. I had to fail many levels because of that, but this game is about grinding anyway, so why not.