Your best bet is to devote 100% of you free time to the game, because it runs in real-time. A huge help is doing long, 8 hour+ projects while you can't play. Assign each of your survivors to those huge piles of garbage in your compund and have them get supplies while you're not on. Multi-tasking. Make sure you have room for the huge numbers of supplies coming your way first.
Otherwise, never have anyone not doing anything. Always have someone do something for best efficiancy.