How not to overspend on groceries

Over the years, I've tried many of the suggestions put out there to save money on groceries. I cook mostly from scratch, shop around sales, plan for leftovers, stock up on bargains, and use coupons. But these three things have been most effective so I don't overspend:

1) Learn the prices for the main items you buy. Some people make price books. I don't. I just get used to the prices. Which leads to the next point...
2) Set an upper cost limit for pricier items. I don't go past a certain dollar amount on some items. I had to readjust when I moved to a different part of the country (right when food prices were soaring), but it doesn't take long to do that. Either adjust or go hungry :-) One of my adjustments last year was joining a warehouse club. The prices were consistent and helped me establish my budget in a new area. Now there are better supermarket sales and our budget has stabilized, so we didn't renew.
3) Pay all in cash. I always take out less money than my budgeted amount. It helps me stick to what I really need and if I forget anything (and I usually do), I still have some money left to get those things later on.