I used to be a tomboy and it can't be a rushed process. You can't just go from G.I. Joe to Barbie Dream house in like 2 seconds. It will catch people off guard, you won't feel confident in it, and you won't understand it.
You can switch it up by dressing edgy with dashes of girly in it.
Try these stores for your "transition:
Buy fashion magazines and rip out pictures of celebs whose style you like. And also just because you're a girl doesn't mean that you have to be a girly girl. There are plenty of girls who dress like girls but don't do the skirts, heels, and pastel pink colors.
Celebs who are Edgy but still look like girls:
Girly Celebs you can get inspiration from:
If you need more help, just let me know here at twitter.com/itsdannidann or email me.