Dave Ramsey's envelope system. We're doing the Financial Peace series at church, and we've started using the envelope system along with a zero-based budget. We love it. It's really helped cut down on unnecessary spending, and forces our money to go to paying off our debts sooner (student loans, mortgage, etc).
PIN THIS! IT IS ABSOLUTELY AMAZING! The Fun Cheap or Free Queen: The 7 bank accounts every family should have. Yes, seven! It will help you budget, organize your life, and save your family HUNDREDS. This was literally an "aha" moment for me and my family finances have never been the same since. It's SO SIMPLE too.