Hello whiffey,
Firstly I would say always make your own powder from freshly ground spices if possible rather than use those jars or premade powders. There are many variations of spices but the main ones are Corriander, Cumin, Chilli Pepper, Cayenne Pepper, Garam Masala, Fenugreek, and a small amount of Turmeric for colour. There are many others such as Onion Seeds, Mustard Seeds, Cardamon Pods etc but way too many to list. Experiment with the mixes until you find what suits you best. The powder should be put into hot Ghee (clarified butter) or butter and oil if you can't get Ghee and fried off to get rid of the powdery taste and also to blend the flavours. Then add your onions and then meat. Use hotter chillies that Jalapenos, go for at least a Thai variety, or India Jwala if you can find them ( I sell chilli plants, bit of an anorak, sorry!) add them and then a small amount of stock to suit whatever meat you're using. Pop the lid on, lowest heat possible and leave for 20mins, stir and leave again until you're happy with the flavour. You may need to add more stock, fresh tomatoes can also be added. Just as you want to serve, tear some fresh corriander and add to your curry.
If you want more specific recipes let me know :o)