That's pretty vague, so here's the best that I can offer:

Pick a basic color that you love and make that your wall color. Then from there pick some good contrasting and/or complimenting colors for the trim, bed, curtains, bedspread, etc.

Once you pick the color that you like for the walls, then take it to your local paint store for them to show you some good options for complimenting and contrasting colors.