Stage oneAsk nicely.
It might hurt your pride, but it is sometime effective. example: "Maggie, Lizzy wants to be alone for a little bit, please leave"
Stage twoAsk no-so-nicely.
"Maggie, get out of my room!"
Offer her chocolate, or some other form of candy.
Stage fourHeaver bribes.
Offer her a hair brushing, or offer to paint her nails (It takes a little more time, but she will leave you alone eventually)
"Maggie if you don't out of my room I will tell mum and/or maul you!"
Stage six.Throw her.
Dragona you should have no problem with this stage.
Give up for a little bit, then start at the top again.
Disclaimer: It is so not my fault if you get in trouble, have to go to the hospital, mum yells at you, etc...