There's no common way to make perfumes.
Most perfumes are similar in how they are prepared.
Now that I've summarized the answer in two sentences, let's discuss what they mean. Perfumes are basically very complex mixtures of chemicals, designed to have pleasing scents, as well as to be stable over time and relatively nontoxic. Depending on the scent you want, you'll need to put different mixtures of chemicals into the pot. Perfume design is traditionally not a very scientific process. Basically, people come up with an idea for a smell, and then they mix chemicals together which, from their own experience, might produce that smell.