If you have been chatting with her for a lengthy period of time, I would hope that you have already shared with her your inability to "pick up the signs". If you haven't shared that with her, maybe you might consider doing so. If she is made aware of that, she may either be more obvious with the signs, or she may decide to be upfront about her desires.

I completely agree with Lilith on masturbation prior to your initial encounter.. by doing so.. it will allow you to proceed slower and concentrate on her needs.

I praise your objective, to make this a memorable experience for both of you.... the best way to do so is to be honest.. caring... and continue to communicate.

Good luck you you..