Like Guitar Hero, you can hold down the buttons as long as you want- they won't fire till you hit the spacebar. Use this to your advantage and get ready for the zombies as they approach.
Give training wheels mode a spin if you find Standard mode difficult (and use the cheats, if you really need to).

Build your righteous bar up by killing zombies.
PRESS THE ALT KEY IF YOU'RE IN TROUBLE! You'll roast all the zombies, have unlimited fuel, and get some breathing room.

Finally, be sure to visit the shops to buy some new gear. It's real hard to beat the game without a zombie killin' hyena.

Hold Q,W,E,R,T,Y to set your zombie traps, press the spacebar to fire them. Press ALT to unleash your righteous guitar-playing skills (once you've charged them up). Press TAB to convert session combo points to Righteousness.

Play guitar, roast zombies, throw them into spinning lawnmower blades, feed them to your hyena,and let your drummer saw them in half with his chainsaw!!!