I haven't got a cooker at the moment so my slow cooker is a lifesaver. I don't do anything complicated and cheat a lot but everything comes out delicious.
For everything, chop an onion and a couple of carrots and put in the bottom.
For beef casserole I add chopped swede, a few chopped up prunes, a Knorr Gravy capsule or an oxo cube. 1 bay leaf, dash of Lea and Perrins, teaspoon of redcurrant jelly and about 1/4 pint of water. Pinch of mustard if I remember. Sometimes mushrooms. Towards the end (to thicken it) I sprinkle some Bisto gravy granules and stir.
For chicken casserole I cheat (because I've discovered it's delicious) and use a Schwartz chicken casserole sachet. I still add a bay leaf and a teaspoon of redcurrant jelly then bung the chicken breasts on top. Sometimes mushrooms and / or chopped apricots. Again to thicken towards the end if required, a sprinkle of Bisto gravy granules.
For chilli, I bung the mince on top of the onion (and carrots if I have any), add an oxo cube or Knorr capsule, a tin of chopped tomatoes and a bay leaf, a few chopped up prunes, some chilli flakes or fresh if I have it, dash of Lea and Perrins then half way through I stir and add a tin of Chilli Beans (kidney beans in chilli sauce).
I also add a teaspoon of linseeds to all my casseroles - they disappear and are good for my insides.