Definitely have the lube ready. I found short girls can take more cock than tall girls in my experience so that would be a plus in my book. Go slow, just give her the tip and work her slowly until she can accommodate it giving her a little more every stroke. I'm 8.5" X 6.25" and have had sex with some very tight virgins. If i can get it in them you can get it in her without a bunch of pain. Lube does wonders. Let her ride you once she is loosened up.