I run a small wargame club and I've been teaching the members how to play Grimdark Future: Firefight. By a long way the most difficult thing for me to teach and the members to grasp is the wounds mechanic. Especially on Tough(X) models for whom we use dice as wound trackers. It seems we have to make two counts: first, we count the wounds being lost, then we have to count the wounds being accumulated.
I'd like to offer a simplification.
Whenever a model takes one or more wounds place a wound marker next to it for each wound. Then roll one die, add the number of markers to the result, and subtract the model's TOUGH value to see what happens:
6+: Knocked Out
This simplifies the game significantly and still gives a Tough model an appropriate advantage. Single models - such as a human guardsman - can be assumed to have Tough(1).