Years (how about a lifetime!) ago, when I was working as a live-in nanny, the children's mother bought me a copy of a magazine which had a removable detailed chart of just about every food you can imagine and what spices/herbs to use with those foods. It's an amazing guide, which I still have in sheet protectors in my binder recipe book. That's how I initially learned what goes with what.

But once I became familiar with the basics, I enjoyed experimenting. My greatest tool is my own nose - I sniff whatever's cooking on the stove, then sniff the spice, and if my nose likes the two smells together, I toss the spice in. It works! I have often smelled the simmering food, then smelled a spice and been so turned off by the combo that I know not to throw that particular spice in. You have to have a sensitive nose, which I do and hubby doesn't, so the sniff-method works for me, but not for him.