Once I've got the major trait I then worry about how the character sounds. I always hear the character's voice in my head before I "see" them. I always have been a radio kind of a person so I guess it reflects in how I write too. Eileen's voice is strident, clear and she wouldn't dream of whining about her lot. That kind of thing is for wimps. Then I start to fill in how Eileen looks. I made her a reasonably attractive character in terms of physical beauty because it explains how, sometimes at least, she can get away with things that frankly someone really ugly simply wouldn't get away with. Combine that with her stubbornness, you have a character who knows to use her assets to her best advantage and if that means using the old physical charms to help get things to go the way Eileen wants, she's all for it. Having said that, Eileen won't do anything that will affect her dignity or could compromise her or leave her open to blackmail but she can get a lot out of general flirting techniques - and does.
It's only when I can really hear my character and know their basic traits that I start to fill in things like what clothes they wear, what colour their eyes are and so on. I find this way of developing characters works for me.