Explaining a lot of the simple things won't really matter, you will learn it really quickly with a bit of playing. Instead I will state the top 3 builds (low-skill)

For each build I will state the path to take and also the upgrades you should do like "0-1-8-8-8-8-0-0" (first number is how many upgrades to take for "health regen", then for the next catrgory and so on)

Best 3 builds

First build: The overlord

Start -> Sniper -> overseer -> overlord

0-1-0-6-7-7-6-6 (meta players will say this is wrong, this is easier to play so I would say this is better but the "better" choice is 0-0-0-7-7-7-7-5)

Second build: The booster

Start -> Flank Guard -> Tri-Angle -> Booster

3-5-5-0-0-4-8-8

Ramming build (instead of using bullets you just charge into them and use the bullets to push your build toward them): 1-4-0-3-7-7-5-7

(Least Skilled) Third build: The Octo Tank

Twin -> Quad Tank -> Octo tank

0-5-0-4-8-8-8-0