Meal plan - yes, I have a set of recipes that are cheap to prepare, and that can be changed depending on whatever leftovers I have (or plan to have, eg a roast chicken makes more than one meal, etc). Cook extra to freeze or use another day.
Checking prices per 100g/ml - yes, the way shops are it can be confusing otherwise.
Buying stuff that you use often in bulk - yes, when I have space. And Dad, just because it's buy 1 get 1 free, that doesn't make it a bargain unless you are actually going to use both of them. (Dad's a sucker for a bargain, sadly. Mum gets frustrated.)
School packed lunches, another one I do. I buy the DCs stuff in bulk and decant into pots to stop them being squashed in the bag. EG, they like the Whitworths dried fruits, so I buy the larger packs rather than paying something like £2-£3 for a few mini packs. I make cakes and portion them. Less additives and cheaper. Instead of a compartmented lunchbox, I use tiny pots with lids, has the added extra of being able to use the pots to save small amounts of stuff in the fridge.
It's not that we are short of funds, but I don't want to waste what money we do have.
Oh, another idea. I have a skin condition called Roseacea and this means I need to use face stuff that has few chemicals and isn't harsh like some cleansers. I ran out of my Ponds cream last weekend, and thought I try the Johnson's baby lotion I still have in the bathroom (well, it says it can be used for dirt and grease). It worked a treat. Face cleaner and less of the redness I often get. Even better than Ponds and a big bottle should last ages.