placing new units, casting spells, etc.
everything except movement
W,A,S,D = movement
numbers 1-4 = use skills
F1-F8 = change unit
R = reload
z/x/c = change menu to skills/aim/weapons
ESC = cancel placing new unit, casting spell
SPACE_BAR = pause ON/OFF
With mouse you can buy weapons and change their settings in aim menu. You can set aim to head (chance on critical), body (chance on stun) or legs Many weapons also allow more modes of fire than only single shots (burst fire, Units are capable to focus fire on first, strongest, weakest or fastest enemy.
At start, when you have friendly units, try to move by creeps. This will help you increase your total done damage and is very essential! Also hesitate to use your skills very often.