The best tip I can give a new player is buy drones on the ground. Most monsters will stop attacking you and try to hit the drones instead which makes the game a whole lot easier.

For commando exclusive tips: Your rightclick and r button both reset your reticle and bloom, so be sure to weave them in when attacking to keep bloom to a minimum. Your dash can be used in any direction except vertically. You can switch targets mid R to stun multiple enemies instead of just 1. Speaking of stun make sure to use your R stun to stop enemies with incredibly telegraphed yet hard to dodge attacks like golems. R also locks onto enemies so its great for killing Wisps that are slightly farther away.