Fire your Multi-Tool with LPM. When out of ammo or charge, use Key Q to melee strike.
Aim (Key F) and Zoom (RPM) to target enemies with precision.
Cycle between weapon modes by using Key G.
Reload your current weapon with Key R. Ensure you have crafted sufficient ammunition before entering a combat situation.
Damage received while on-foot will first deplete your shield. Your shield will recharge over time. Take cover and avoid taking damage while the shield is low.
Purchase plans for a Personal Forcefield at Technology Merchants. This is a powerful combat shield deployed from the Multi-Tool.