1. Spend a few hours in the kitchen
In just over an hour I can prep/chop salad ingredients for my lunch salads all week, make clam chowder and popovers for dinner, and make my husband's sandwich for tomorrow. It's a small investment of time with a large payoff. We'll have leftover soup for tomorrow, lunches for the whole week, and will have saved ourselves well over $50 eating in for breakfast, lunch and dinner.
2. Plan a menu
Ideally this should be done before #1. If you go through your pantry, freezer and grocery list, and figure out what you are going to eat for lunch and dinner from now through next Saturday, then there will be a significantly lower likelihood that you will get take out, or spend money eating out. Eating out isn't a bad thing in moderation, but it can be a budget killer.
3. Track your spending
Every penny out, for the whole week. Most of us spend mindlessly from time to time - even those of us who are hardened budget users. Looking at the numbers periodically often serves as a nice dose of cold hard reality - one that will help you keep that debit card in your pocket.
4. Make do with something you have
The insidious convenience of a store on every corner is that when we need something - to eat, to accomplish a project, or to wear - we can just run out and get it. The next time you find yourself thinking "I need to just run out and get....", don't. Instead, find something you already have that will work just as well. Out of picture hooks? Try a nail. Polish your shoes instead of buying new ones. Switch up an outfit instead of getting a new one. Just because you always wear the red shirt with a particular pair of pants doesn't mean you can't change it up now and again.
5. Turn off the TV and do something else
Study after study correlates our spending to our TV watching. The more you watch, the more you spend. So turn off the TV and darn some socks, go for a walk, learn to bake bread, or iron a shirt instead of sending it to the drycleaner. Even better, read a book. You'll spend less, get something on your to-do list done (even if it's just the fresh air and exercise you get from walking) and maybe sort out some of the things on your mental back burner.