When you decide to go shopping, grab a bite to eat first. I have found that if I am hungry when I go shopping then I will either buy things that don't need or just flat should not have gotten. This tends to be both bad for the budget and my waistline. A hungry stomach is not a good shopping partner.
I have also found that making a shopping list is a big help. A shopping list works even better if you are determined to stick with it. If you go shopping without a shopping list, you will most likely buy more than you expected or maybe can even afford. Always stick to your budget.
You may even want to take a friend along with you on your shopping trips. It is harder to buy things that you don't need if you know that someone is watching you.
I have also found that discount grocery stores can provide excellent savings. Many times, you will find items that are half the price of normal grocery stores.Always check the dates on items and look for punctures in the containers, but all in all these stores can really help on the grocery bill.