Do not try to speed up the process by increasing the heat. It wont take long for the spices to burn.
Do not worry about the perfect measurements. A little here and there is completely fine.
To preserve the aroma and freshness make this in small batches. All you need in one teaspoon per curry which serves around 4 people.
Some curries require this mix to be added to oil during the initial sauteing while others require it to be sprinkled on top at the end of cooking.
Garam masala is mainly used in meat preparation. It also tastes good with roasted vegetables.
I make enough to last me about 2 months in one batch (about 3/4 cup).