Some playwrights believe in coming up with elaborate histories for their characters, exhuming every tiny detail of their lives, before they write a word. Noted dramatic writing "theorist" Lajos Egri talks about a character "bone structure," broken down into the physical, social and emotional realms. My old mentor, William Alfred, used to talk about a "police file."
All of these are perfectly valid ways to compose a character, but what if, for whatever reason, you decide that such an exhaustive look at a character
The first is the "master gesture." Pick some defining gesture for your character
The second method is to pick three words to describe the character. They can be adjectives (e.g. "cruel," "kind"), nouns ("taskmaster," "ogre," "babe magnet") or any other part of speech that makes sense. Just like with the master gesture, working from these three words, you can expand the character outward.
Feel free to mix and match these "fast food" character development methods with the more traditional ones until you find the right comfort level for your writing style.