take it slow.
be very gentle with her.
as someone else said, watch her facial expressions. if it sounds like its too much, back off.
foreplay is quite good in this situation. not like crazy shit, but atleast good enough for the next step.
and as someone else said, lubrication can help too, just to make things "flow" better.

good luck.


p.s. - im not sure im really liable on this topic.