When I use cumin I like to wake it up first by hitting it for a bit in a hot dry pan. Might not need as much as you think.

Cumin is when you want anything to be earthy.

Cardamom is best used exclusively to flavor white rice, when your gonna be topping it with other powerful flavors that you may want to counter.

Cumin is a bedrock Tex-Mex spice. I use whole cumin seeds as an alternative to caraway when culturing sauerkraut. Lends a district earthiness and partners particularly well with street tacos.

I cant school you, but all I have learned is more than you think is better.

I have used cardamom in a homebrewed hard soda years ago.

I think I also use it to spice a mulled cider (alongside other wintery spices).

I only ever use cardamom for making pajeet chili curry. Cumin's a staple in Mexican and tex-mex. Put it in everything. It works well with a lot.

All I know is that when someone knocks on my door I tell them to cumin

Cumin seeds cook extremely well with onions if you're grilling them. The smell is gorgeous and they're good for your gut. Cardamon is if you're making something like a curry, best put in later on in the cooking just before adding sauce (again, grilling) so that the seed remains mostly intact but the perfume is expelled, then once it's finished you fish around for the cardamon seed and take it out because you don't want to eat it.

I highly recommend grinding your own cumin and cardamom at the time of use. Don’t get the store bought ground kind get the cardamom pods and the whole cumin seeds They both have micronutrients that start to degrade the longer they sit in a ground state. Also the flavor is way more intense when you grind your own so you might want to start by adding less than the recipe states they are probably using the store bought ground stuff.