im not too sure about it the finer details myself but the way i see it is this
killing incapped enemy with meele +20
killing incapped enemy with gun +15
guarding (basic) +5
guarding(primary) +5 - +10
hacking (basic) 1-5
hacking (primary) 1-10
turret(full kill 1 person) +30 any more add another 30 per person fully shot down
disarming HE charge +5
disarming hack box +5
(if anyone has better information please correct me)