Thrifty Mommy published a list of 50 ways to save money on your grocery bill. She has some really good advice in here, some of it is obvious (check sale flyers and use coupons) and some are ideas that I didn't even know were options. Did you know you could get rainchecks for out-of-stock sale items? You can come back later and get the lower price even after the sale is over.
How about not going grocery shopping hungry? That is always one to think about. I remember one time I went to the supermarket dying of thirst and I ended up buying milk, water, lemonade, beer, orange juice, coke and fruit punch. I really could have been very happy with just the milk, beer and water.
She also suggests buying store brands. I have very mixed feeling about this. For example, I know Clorox makes the Publix brand bleach. It is safe to buy Publix bleach. I think most canned beans taste similar. I've also had terrible luck buying store brand dishwashing liquid. If it takes eight times as much soap to wash your three pans, you aren't really saving money in the long run. What are your money saving tips at the grocery store?