I can and do make my own blend of curry from whatever spices I have available at the time. These include cumin seeds, coriander seeds, dried chillies etc etc etc and there are as many recipes available as you can shake a stick at.
In view of this, I will keep my tips simple:
1. Always fry whatever spices you are going to use as a first step. I use a fair amount of olive oil and then add small amounts of water to stop the spices burning or sticking.
2. Next into the pot is chopped up onions. They are fried in the oil/water mixture along with the spices until translucent.
3. Next is the garlic, which is fried until it starts to turn brown. (Not easy to see in amongst all those spices and onions.)
4. At this stage it's worth deciding exactly what you are going to have in the curry. It can range from:
A) Vegetables (squash, potato, carrot, peas, green beans etc etc) which are eaten on their own.
B) Meat (chicken, turkey, beef, lamb etc.) which is eaten accompanied by rice and/or naan bread.
C) Additions such as desiccated coconut, dried papaya, sultanas, raisins, pineapple etc to give that bit of sweetness or crystallised ginger to give it that bite of "hot sweet".
5. If meat is being used I cut it into bite sized pieces and brown them in the oil/water and then add the stock.
6. For vegetables I add the stock first and then put the vegetables into the pot in the order of "longest to cook in first" when the stock starts to boil. An example would be "Carrots > potatoes > sweet potatoes > squash > green beans > red peppers".
7. The stock is usually hot water with a couple of Oxo Cubes dissolved in it. There should be sufficient stock to just cover the meat and/or vegetables.
8. When the curry comes to the boil I have my first taste of whatever is in the pot and depending on taste I will add:
o More Chilli powder if it is too mild.
o Salt and/or sugar to balance the taste. (If you make the curry too hot for your palate the addition of sugar or syrup will reduce the heat.)
Finally it's a matter of tasting and offering tastes to SWMBO until we are both happy with the result.
For a really luxurious taste (usually when we have visitors and especially if we are making a Passanda or a Korma) we stir in a tin of coconut milk.
The variety of curries that can be made is enormous, as is the variety of edible things that can be included. I find that my most memorable curries ("memorable" in a nice way) are those that are knocked together and have included everything from whole tomatoes to mushrooms to chickpeas to sweetcorn .... the list of components and their combinations would run into many thousands ...
... which is why most of them are unrepeatable!
Oh, and only
ONE of them has finished up being partially dumped!
I bought some spices in India and cooking a beef curry I overdosed on Tamarind Paste. I had to remove the chunks of beef, rinse them in cold water, pour all the stock down the drain and start all over again; but this time without the Tamarind Paste!