Lets Jump Straight to the Point.

You are new to the game, start with the Boomerang Lass - Hildr.
Reason? Being able to hit more than just the mobs in a line from you.

Try to get the following upgrades, in priority order

• Barter (shop discount)
  
• Cooldown (until lvl 5)
  
• Magic Missile
  
• Magnet
  
• Odin's Orb (until lvl 5)
  
• Volley

Do not re-roll when you get to the shop, save your coins, you'll need everything you can get.
Other upgrades are great too, but those ones will carry you far.
Naturally, get some HP regen, HP boost, and whatever else you fancy. It doesnt matter TOOO much, as long as you can get a quick firing, clearing spell.

From my first run with Hildr I obtained 500 gems
Volley was good, Ballista was also good, Bouncy Lines was a nice addition
I had 562 hp max, and 30 points of armour, but at wave 50+ mobs hit for 50+ damage anyway and are FAST.

NEXT: How can we get those upgrades if we just keep dying? What are the RAW Tactics? Let's Cover That.

(Oh he said the name of the guide!)

Firstly, Run in Circles. Do You Doing Games.

When you get to Wave 30+ (maybe?) Mobs start to be a bit WILD and Numerous.

Your unit, has a non-spawn area where mobs will not spawn.
Mobs will spawn typically on a timer.
Thus, If you keep yourself, roughly 10 in-game paces away from each corner, you will not get attacked from behind / underneath, and can focus fire ahead of you.

If you then walk slowly up and down the edge, firing off the Odins Lazer, you'll clear mobs quick and in clumps.
As soon the mobs spawn, Blast a few with Odins Lazer then RUN!
Run in a loop into the mob area, collect coins, and run back out to the corner, ready to blast Odins Lazer again.
Rinse, Repeat.

- this will get you to Wave 50+ At which point mobs get too fast to keep this tactic up as easily. upgrade then try again if you want to get further than this.

Sometimes, if you have health, and it's near the end of a wave, it will be worth weaving into the middle to try collect coins, but overall it is better to be safe, unless it's before a boss wave, then jump into the midst of the coins.

With bosses, try to finish the fight near one corner to give you all the time to collect every single coin.