I used to just go to my favorite grocery store and get what we needed - well it is just too expensive now.
My husband and I sit down and read the sales ads on Thursday evening. Sale prices really can vary by store. I make a list with categories for each store (sometimes as many as four) - it is more work going between stores but you really can save a substantial amount of money.
After the list is made I make a menu for the week and add things to the list if needed.
We divide up the shopping - for example I will go to one store during the day on Friday and my husband will hit the other three on his way home from work and we stick to the list.
We buy meat approx once/month - usually when on sale and cook and freeze for sandwiches as some of the others mentioned. We also buy 10 lbs ground beef when on sale and divide into one-ound packages and freeze. We only buy soda in liter bottles - cans are a waste (esp if you have teens).
It is also helpful not to take the kids along when grocery shopping - mine ask for everything they see and it's hard not to give in.
I have a small container in the kitchen cabinet where I drop coupons for things we regularly use.
thanks for asking such a good question!
W.