If you use whole spices, temper them first in a dry pan, a minute or two, to release flavors.
Allow spices to cool.
Grind whole spices in a spice/coffee grinder or mortar and pestle or small blender one by one.
Mix all ground spices together in a bowl.
Store in an airtight jar, in a cool and dry place. Keep away from direct sunlight.
Notes
If you have to dry the fenugreek and curry leaves, dry in a dehydrator or in the oven only.
You can use ground spices too. In that case, just mix all the ground spices together.
Some spices do not need to be dried to grind them, such as nutmeg. Just scrape off with a nutmeg grater or a knife.
It is always better to use quality whole spices, to temper them, so to release the aroma and to prepare smaller batches instead of larger quantities. This is because the quality of spices, and their flavors, deteriorate in time, especially ground ones.