don't assume close order formation 100% of the time though... obviously if your opponent has no blast/template weapons at all then have a field day with! but if there's any of those nasty types of guns in the enemy army, stay spread out!!!
keep in mind you can always assume close order formation when you assault
just make sure all your models end up in base-to-base contact with eachother!
iron discipline can also be an army saver... it basically allows your officers to give a near-marine equivalent Ld ability to all your squads in range.
also, look into die-hards if you're worried about your men legging it once they get stuck in. i've had a single guardsman outnumbered litterally 20:1 stay and fight thanks to that doctrine!
cheers!