First decide what type of curry. Burmese curry starts with onion blended to a paste. Indian curry is different in different regions. If you have a local take away you like ask them their heritage. Where I am it is mainly Punjabi and Bengali people who have take aways.
Do you want a dry curry like Bombay potatoes or one with a proper sauce?
I agree with ghee (also great for sortieing potatoes) but an oil with a high smoke point can work.
Assemble your spices. Some are going to be fried in the ghee, some added later and a couple towards the end (garam masala).
Chop or slice onions, chop or grate garlic, the garlic gives the heat so adjust to taste.
Meat? Fish? Veg? All take different times to cook. You get a better flavour if the meat is on the bone.
Put ghee / oil in the pan and heat, put in your starting spices, for me this is usually whole peppercorns, coriander, cumin seeds and onion seeds, possibly fennel seeds. Basically and whole spices I want in my curry, these will start to pop as they release their taste / aroma.
Add onion and garlic with a teaspoon of ground turmeric and ground cumin. A teaspoon is enough if the spices are fairly fresh, they loose their flavour the longer they are in the cupboard so adjust.
Add the meat / veg and any other spices you want to include, coat the meat / veg in the spice mixture.
Once coated you need to add liquid. This can be water or stock or cocoanut milk. I tend to use water and if I want a cocoanut flavour I will add creamed cocoanut later on. You can also use passata, it's not traditional but it does work.
Now leave it to simmer for as long as you can. You want to reduce the liquid until it coats the meat as a thick sauce.
Taste and adjust seasoning. If you need to add more spices then add a little more liquid, simmer until you have the sauce you want.
Add the garam masala and simmer for another 10 mins.