What do a parrot, an eye patch, and a wooden leg have in common? Pirates? No, cheap and easy ways to create instant characters.
It always amazes me when creative writing courses talk about giving 'depth' to your characters as though they were submarines. They talk of emotions and complexity. Pants to that I say!

I'll mention no names, but we're all familiar with those books that take an age to describe a minor character, only to have him vanish without a trace.
Similary, we're all familiar with the cut-out characters of cheap thrillers and the stereotypes that seem to stink the place up.

My method is to go straight down the middle and offer the best of both worlds. To do that, we'll concentrate on the simple stuff, the obvious stuff.

So you have your character, for the sake of simplicity. we'll call him X.

Now, let's give him a backstory

1. Accent - where does he come from? Is he home or somewhere else? Why is he away from home?

2.Facial scars - how did it happen?

3.Disability - he's in a wheelchair. How did that happen?

4. Is he tall or small? Did people give him nick-names because of his height?

5.Wedding ring? How long has he been married? No wedding ring - what happened?

And so on and so on. Now, not every character will have a scar on their face, and not every character will be married (or want to get married) but the principal of creating characters is so simple, it's a wonder why people need to blog about it or offer creative writing classes about it :)