First off I suggest taking a good look at your pantry. Having a solid pantry will help with running to the store between real shopping trips. I have started shopping at Aldi for a lot of my pantry staples, things like sugar, flour, chicken, beef, and veggie stock or broth, cream of mushroom soup, cooking spray, baking needs, bread crumbs, nuts, dried fruit, lots of good stuff and a really good price. Make sure your pantry is set up with how you cook and live. Also make sure to have things like foil, baggies, containers for left overs.
Look at the your store AD for the week, special items or BOGO's, Use whats in season in the produce sections, as well as at the fish counter if your store has one... sometimes things are in season and are a great price.
Live by the list... make the list and stick to it... okay so with this said, if there is a good deal on meat, or family packaging is a better deal get it, and divide it up. Or some in store special then take a look and make sure you know what you are going to do with it... last week I bought a huge family package of ground chuck, I took it home and made meatloaf for dinner,and with the rest I made meatballs and froze them ( 120 meatball ready to go) , I made basic meatballs, I can use them for meatball subs, in red sauce, throw into some soup, or make my meatballs in a crock pot for a party or whatever.
Meal planning, try at first to start with a couple of days, then a week, then 2 weeks, then monthly... Look ahead, at the calendar, at what you and your family have going on, or a celebration or your turn to provide snacks or a covered dish for work.
Another thing that I find will break the budget, is holiday meal, or if your have guest coming to visit. This is were you need to plan ahead. If you know that you are going to be baking up a storm start weekly picking up stuff, like the "good vanilla" or if flour is BOGO this week, get a little bit all along then your not spending 100.00 buck on baking stuff.
Freezer meals, such as soup, stews, meatballs, taco meat, shredded pork, beef or chicken for quick meals, which helps with going to the store in between.
Make your own grab and go breakfast item, muffins are a favorite item to grab and go, your own granola mix...
Coupons are another way to save. You don't have to be a super couponer, just check out your list, and see what you might can find ( coupons.com is a good source that you can just print off), check the store ad to match up coupons this way, if your store offer in store coupons, can you stack them - most will let you.
You have to keep at it... but once you have gotten the hang of it. It does get easier and becomes second nature... I have been doing it so long that its just how I shop.