Use cheaper cuts of meat - for example chicken thighs/legs rather than chicken breasts. Do similar with fish rather than salmon try um basically anything else. Things like sardines are particularly cheap.
Add small amounts of strong tasting foods to add flavour with little cost, e.g. adding chorizo to chicken dishes (and halving the amount of chicken) -obviously this wouldn't work with something like coq au vin 
. You can do the same with cheeses - rather than topping something with grated cheese, top it with breadcrumbs with a bit of parmesan mixed in.
Bulk out meals with veg and pulses. You do need to choose your veg carefully - remember tinned and frozen are often cheaper and nutritionally fine (frozen can be better than fresh). For example bulk out a curry with some lentils and 1/2 a tin of spinach.
Make sure you are sticking to 1/4 protein 1/4 carbs and 1/2 veg plates.
Some fruit and veg is expensive but others is cheap. Buying peppers individually is expensive, but you can get multipacks of cheap peppers. They tend to be nearly all green. I tend the one nice coloured one for salads and chop up the green to be cooked (as it doesn't make as much difference then). Carrots/potatoes/frozen peas/broccoli/swede/cabbage are cheap veg - apples(depending on variety)/oranges/bananas are cheapish fruit. Stick to these and add maybe one or 2 more expensive ones as a treat item.
Give yourself a small budget for buying new/interesting ingredients and make sure before you buy any you have enough recipes to use it up.
Bulk cook and freeze spare portions as quick ready meals for when you can't be bothered to cook.
Don't waste anything - cook/freeze if necessary. Make sure you are only buying what you need and no more. If you are regularly throwing stuff out, look at what you are chucking and where you're buying stuff you don't use. If you are serving too big a portion and its getting chucked that way, start giving half portions and letting people help themselves to more after if necessary. Any leftovers should go into another meal. We often use them for lunches - I buy very little for lunches assuming we will scavenge what we have in.
I love cooking and trying out new recipes, you just have to set yourself a challenge with a maximum budget for each meal.