Tip #4 Menu Plan!!
This is a relatively new concept to me. It's so incredibly easy I can't believe I haven't been doing it my whole life! On a Saturday or Sunday afternoon, I survey our pantry, freezer, and fridge and make a mental note of what we have. I'll then look through my recipe book or head over to allrecipes.com to come up with 5-6 meals for the week.
If you are just starting out with this whole concept of saving money while you grocery shop or if you don't have a stockpile of supplies built up, you'll want to look at the flyers/ads before you go to the grocery store and base your meals off of what's on sale that week.
Another thing that I did that I've found really helpful was to make a list of our favorite meals/recipes in Google Docs (and link to the recipe if it's online). If I ever need any inspiration or feel like I'm in a rut, I'll just pull this up and cook something from this list.
If there is a recipe that calls for a lot of prep-work, I'll make that recipe on the weekend or I'll at least prep some of it on Sunday so it requires less time during the week.
If you're interested in reading more about menu planning, there are some helpful posts here and here.