Shooting is key to pretty much every wargame, and shooting often adds a huge amount of complication – ranges, rate of fire, armour penetration, line of sight. Not to mention in any turn based game which ever side gets the first turn is often able to cripple their opponents force before their opponent can return fire (in my opinion the biggest downside to 40k). In the interest of avoiding complication I drew up the following table for my games of Deathzap:

By way of explanation, you can see we have a standard roll to hit, roll to save system. The roll to hit is based on the cover the target is in. I’ve also boiled all weapons down to 5 types, and all targets down to 7 types. I’ve put things into a table simply because I prefer a table where possible over a list of modifiers to remember.
To avoid the turn 1 massacre, during the shooting phase of the turn both sides shoot, with the fire being simultaneous, meaning both sides shoot and then casualties are removed from play.