If you need to fry powdered spices always mix them with a little water first (aim for the consistency of ketchup) as this will stop them burning as easily.
When using whole cardamom seeds in a curry always pop them open first so they release their flavours. Use the back of a spoon and press down gently. Remember, you only want open up the seed a bit, not crush it completely.
Garam masala produce a wonderful aroma. Always add it towards the end of the cooking process and not when you add the other spices to ensure you get the full benefit.
When cooing onions sprinkle a small bit of salt on them to speed up the browning process.
When a dish requires whole spices to be tempered in oil (tadka) you need the oil to be very hot to extract the full flavour from the spices. If you put the spices in too early you are wasting your time. To test if the oil is ready drop one cummin seed into the oil. If it fizzes and jumps straight away the oil is ready. If not, then patience, patience…
When a dish needs fresh coriander then mix the chopped stems into the sauce (because they have more flavour) and keep the leaves (broken, not chopped) to sprinkle on top at the end of the cooking.
Throw old, stale spices away. Sounds obvious but too many people still try to flog the last bit of flavour out of dried out spices. In. The. Rubbish. Bin.