For background colors it depends on what color you'd like for the character, but I suggest something earthy if you'll color her with warm colors/pastel (a bit more neutral)
But if you're going for a cold colors then something grey/dark pale purplish will be good? You can combine the colors and see which is better before shading it (try changing the hue and saturation etc)
Sometimes giving the background a flat color/just typical white will work out with the right combination, or adding a bit of ornaments?
And for hairstyles, there are lot of references on google, but I suggest hairstyles that show the flow of her hair (for the sultry looking)
You can change it a bit by shortening it on some sides or adding a braid etc. Just try experimenting! It'll be fun to see how it changes with different hairstyles.
Sorry if it's a bit messy (typing from phone lol) hope it helps even just a bit!