Well, I just use regular girl clothes. But ive only started dressing as a girl a few weeks ago, since I had to get MY mom to come around to the idea of me being her daughter first, but I did makeup before and I do a good job so that's important. Idt there's such thing as tran sgender teenage girl clothes. They're just, you know, clothes. But I just kinds go for loose shirts because I hate my flat chest and male build. As for pants and skirts. Just have her tuck for jeans, and for skirts too. Buy her the basic under-wear and panties. But yeah, just regular girl clothes. Teach her makeup and stuff so that she you know pass better. Oh and I'd like to thank you since you're helping instead of you know, giving her the boot out of the house. This is very good thing you're doing here. I remember a couple weeks ago when my mum bought me my first, "girl " shirt I was so happy.