1.) Ditch the sandwich baggies - having a reliable set of Tupperware will save you money and spare the landfills from your bags when you're done with them.
2.) Buy a timer - Time your showers! I know how hard it is to avoid taking long, hot showers, but setting a timer should help remind you to turn off the water!
3.) Invest in a Brita - Unfortunately, I'm one of those people that gets grossed out by tap water. So instead of buying tons of bottled water, I've bought a Brita filter to handle it.