Sounds to me like you are already on the road to change. 1st, pat yourself on the back for identifying a destructive pattern and for having the guts to confront it and change it.
Having said that, the first thing you can do is to greet each person with a smile and look them in the eye. I like to start out each conversation with a compliment.
And another thing you can do is dress in soft colors. Bright or bold colors appear sharp and give the impression of a calculating person whereas dressing in softer colors such as pink, yellow and pastels often give the impression of compassion and emulates a gentle soul.
And lastly, remember, you're a girl, don't run from it, embrace it. Don't be afraid to be girly. And remember, boys will like you regardless. We guys, we can overlook alot of things. You are 12, when you are 14, youll be writing a Yahoo Question talking about how to make boys leave you alone.
Remember, the change comes from within and you have begun that process by taking this step. You have admitted to yourself, what you have done incorrectly in the past. It takes a strong person to see this and to act on it.
Please let us know how you do... And God Bless
