strega42 has been doing a post on food for those who haven't got much, and who perhaps haven't done much cooking before. This inspires me to offer up what little wisdom I have to offer on the subject, derived originally from some wisdom that my father passed to me.
This was that most classic dishes, and even entire ethnic cuisines, have specific signature tastes or key ingredients that make them what they are. You can change a lot of the other ingredients around, swap out other flavors like a gambler rolling dice, and somehow it'll still have that... flavor. Get everything else right but leave the key out, and it'll just taste wrong.
On the individual level, one of the most clear examples of this I know is the difference between spaghetti (red) sauce and pizza sauce. The signature or key for spaghetti is oregano, the key for pizza is basil. You can make a sauce that says clearly "spaghetti" and another that says clearly "pizza" by just reversing the proportions of oregano and basil and keeping everything else identical. (My spaghetti sauce is very much not pizza sauce in other ways, but a simple red sauce can do both with just slight seasoning tweaks).
On larger cuisine levels, there are very common signature flavors that show up. Mexican food has several, but the two most obvious and crucial in a number of dishes are cumin and cilantro, with corn flavors also playing a large part. Indian (subcontinent) food commonly uses a particular spice mix called "garam masala". Chinese commonly uses ginger and soy.
That doesn't mean those are the only important flavors, or that some dishes won't use those flavors. It just means that those flavors can *evoke* the impression of the cuisine.
Experienced cooks might consider this too obvious, so obvious as to be insulting to tell them, or (quite correctly) oversimplification. But for a new cook, or one who hasn't thought about it, this can be a revelation; it was for me, when my dad told it to me.
THINKING about the flavors is hard to do when you start out, yet if you don't think about it, you won't be able to make dishes that do what you want.
I have to go shopping, but I'll have some more general thoughts about cooking that I've learned over the years. Some will be very useful for new cooks, some perhaps you need to wait until you're either not new, or have more money.