This is a general guide that will beat almost every level on hard, just add the towers when you can afford and buy banana farms as you need them.
Start with 2 darts then add 2 more
Upgrade 2 darts to triple shot with camo
Add 2 boomerangs with the bionic boomer at the start (for lead)
Upgrade the other 2 darts to camo/triple (gets rid of most camos till you get village)
Add super monkey with plasma and a village with see camo/range
Add 2 or 3 cannon with bloom impact (impact cannons are a must)
Upgrade super monkey to sun god or robo
Sell the darts and boomerangs if you need to (they don't do much anymore)
Keep adding more super monkey sun gods or robos and a few more bloom impact cannons
Some maps you can throw in an ice tower if needed
Win.
There's basically 2 parts to this game, getting to level 50 and past it. You become almost invincible at 50.
The easiest way to 50+ is vampire lightwielder (sanctify doesn't heal monsters), the best past 50 is golem cursed as the only stats that matter are resists.
Try and get 100 ice resist and at least 50 in others asap, makes getting to 50 easier. After level 20ish about 1/3 of monsters are ice so with 100 ice resist they do zero damage.
The only titles worth it are the 10% and 5% runspeed.
Every monster is one hit one kill after about level 100.
I quit at level 220, with 700+ armour, 800 strength and a 722 damage weapon doing 16000 a hit and healing around 2200 (as vamp).