These are two basic questions about one of the most varied and tempting dishes of the world. There is no real answer, the word has crept into the English language and although everybody has an idea of what they themselves mean by a curry it is really only a general term used to describe a whole host of very varied dishes.
What makes a good curry? Well, beauty is in the eye of the beholder, or one man's meat is another man's poison are very apt expressions than can be applied to curry. So, what is a good curry? It is whatever you personally enjoy, the combination of spices and ingredient that you enjoy. Nothing more nothing less.
So how do you make a curry? Once again, this web page can only outline for you the basic ideas of what has been found to work for other people and then encourage you to try out your own modifications to suit your own particular tastes and preferences.
Be prepared to experiment! If you find that you have not got a particular spice listed in a recipe, think about other spices that are a little bit similar and replace with that one. Yes, I agree that it will not turn out like the recipe in the book, but you may well find a flavour combination that suits you fairly well.
Experiment is the key to improving basic recipes and producing that mouthwatering dish that everybody wonders how you make it. One of my own experiments was to use the dried fruit of the nutmeg tree, something I had never seen in any book or recipe for curry. The result was particularly interesting and palatable. Dried nutmeg fruit (Halua Palua in Malay) has now become a treasured ingredient in our household when we wish to give a slightly different lift to our curries.
Most people associate rice with curry but it is not necessary to eat rice with a curry. For real fun try eating a curry without any cutlery and using chapatis to scoop and mop up the curry, as Mike Harding would say Ooyah Ooyah dip your chapati!