Use small grocery bags with handles to hang on your window levers for your garbage. Freeze your small containers of juice or water to serve as additional freezer packs in your cooler. Helps keep the drinks cold, too. Keep a damp cloth dipped in lemon water inside a plastic bag to wipe your hands while you're on the move and snacking in the car. Always ask if there are cheaper rates.
Airlines frequently overbook.
If you volunteer to get bumped out, they may give you compensation like a discount off your next trip. Book your flight in advance or during airline sales. Try to travel during low season. If timing is not important, you can try last minute deals. Check for specially priced days or times.