The basic rule in combat in real life can be broken down to 'no fire without movement, no movement without fire'.
This means: Split your squad into at least 2 fireteams who cover each other. one moves, the other shoots.
Next point: A machine gun is useless in dynamic combat. place it somewhere (preferably flanking the enemy), let it fire some bursts and let it change position and repeat that (also here can be use 2 mg in a squad, covering each other, if there are enough men available).
Another (pretty elegant but also difficult) technique is sometimes called 'guerilla tango'. It's a special kind of hit and run: try catching the enemy's flank, firing a few bursts. when the enemy starts to regroup, you regroup yout team to get into the enemies flank again, and so on... Maybe I draw a sketch later
