>>537785614
During wave 1, savescum until you get the following buffs:
>1 more shop reset
>3% coin interest per at the end of the wave
>20% discount on traps (not required but helps if you get early)

During wave 1-5 beat all monsters with just fusion ku-robot (pea shooter) and aero ku-robot (air blower). Don't set any traps and conserve coins.
During wave 6-15, do the same as above except set 3-4 electro ceiling traps (500 coin each) as backup.

When the shop becomes available, do the following:
>buy HP+5 item
>reset shop
>buy HP+5 item
>reset shop
>buy HP+5 item
>Use them all immediately so your inventory don't get full

During the early stages, these HP restore items cost 0 coins, they become 600 coins afterwards, then 8000 late game (wave 21+). So make sure to stock up early while they are still cheap. You can get up to 100 HP this way, which means you can tank up to 9 tambourinist and floatist (they do 10 damage each).