Hi, I have 2 tips for you:
1. Go to a professional stylist. He/she will give you some advice on your face shape, skin tone, and the right hairstyle for you.
2. Lighten up your hair gradually during several months. Choose a lighter colour for your hair than it is now and each month go brighter. This way your hair will not get damaged and you will be able to decide if you even like yourself with light hair.
Good luck with the change and remember, the most important thing is for you to be happy