Use two shades of the same color (light and medium pink), to create a beautifully soft, dynamic effect. For contrast use one in high-gloss and the other in satin finish.
Safe bet is yellow or a current popular color is a "barn red" color. A technique that that is very neat with stripes is to use one color but mix the finishes. For example, use a flat finish for one stripe and a gloss for the next and vice versa. It is very subtle but so very neat.
A couple of pairs of colors that are good for girly stripes are dark pink and light pink, Dark purple and lavender. You can even do a sage green combination.
If your daughters room is small you should choose lighter colors so the room doesn't feel too crowded. If the room is larger you can choose pretty much any color. Toddlers love bright colors so choose a color that is stimulating.