@GoodFortuneAttendThee it's hard to say really, it depends what you are making..
Chilli - I always use a 4 spice combo, cumin, chilli powder, smoked paprika and chilli flakes, plus salt & pepper, garlic & onions. Sometimes it's a little too beefy or tomatoey so I'll adjust either way with a spoonful of gravy powder (or similar) or ketchup/tomato purée. I find a little bit of dark chocolate or instant coffee adds a nice richness.
Curries - TAKE YOUR TIME!! Slow is key, roast whole spices (onion seeds, mustard seeds, cumin seeds etc) in a little oil until they pop, then add onions. These need to be cooked quite a long time to really soften and sweeten before anything else is added. Tikka masala paste + cream of tomato soup makes a great curry sauce as the cream is stable and won't split! I really prefer using spice pastes + liquid (coconut milk, tinned tomatoes, whatever you're using) as opposed to jars of curry sauce, you get a much better depth of flavour.
Stews - brown the meat & onions first. Cook low & slow. Add lots of herbs, maybe a bouquet garni or similar whole herbs to be taken out before serving. Add any veg in nearer the end or it will be mushed into nothingness by the time the meat is done (unless you want that of course!). Add wine/ale etc for flavour near the end or it will all cook away.
I love using ketchup in tomato based sauces because it adds a nice acidity and has seasoning in it already.
Herbs and spices are your friend, use them liberally! Often if things taste bland it's because they are under seasoned.