As another poster mentioned, this topic comes up pretty regularly....if you do a search for "budget" or "cheap meals" or something like that, they should come up. There are tons of great ideas on them.
For me, it was a process, not an overnight thing. I tweaked one family favorite meal at a time, keeping some ideas and discarding others that didn't work so well for us. I tried new things once a week at most, to keep the grumbling to a minimum. The hubby and I still discuss the use of ground turkey instead of beef---he insists he can taste the difference, but he only catches it about half the time, so I continue to use it
My biggest tips would be: get to know what rock bottom sale prices are for your area; look closely at the sales ads for your nearby stores and plan your meals around the best deals; stock up when you see a good deal on stuff you use a lot; look into using coupons--they can save you a ton if used with a good sale; and buy the produce that's on sale and in season--you'll spend less and it tastes better anyway.