Good morning! No buy is awesome because you can make your own rules based on your personal situation, but most of us don't count "set" bills, like the house payment or gas bill.
For me, it was not as much about getting no buy days as it was staying under budget. So I added up all the bills that I have to pay, and subtracted that from how much I make. That gives me the amount I can spend on non-essentials, including food.
That number is usually $800 or $900. So my goal is to stay under that number no matter what. The first month I did No-buy (May) I was shocked at how much money I wasted on trivia like magazines and cleaning supplies. My grocery spending was very high for only 2 people.
In June I got serious. I started couponing and going to sites like Southern Savers. I now track my total spent for the month, how many no buy days, how much I spent on groceries, and how much I saved on coupons/sales.
Others track how much budget they have for eating out or gas. Its up to you.
Since I started tracking in June, I have saved $1250 on groceries/ cleaning supplies, etc, which is about $200 a month. I also have a Christmas club that I put $100 a month in, and an online savings account that I put $50 a month in. I'll be raising that amount this month when the social security tax cut goes into effect.
I paid off about $6700 in credit card debt this year as well.
No buy opened my eyes to how much junk I was wasting money on. I think it works best if you write down everything you buy, because that is how you will find out what your money weaknesses are and start working on them.
Don't give up after the first month- the first month is a trial run to see what your spending habits look like, and the 2nd month you can start making some adjustments.
Good luck! We will be there to support you.