I emailed a provider and she emailed me back asking more information about me. I told her  I wanted to set up an appointment and she never emailed back. How do I let her know I'm serious and will pay.

Did you give her the information that she asked for?

You let a girl know that you are serious by following her booking and screening procedures.  Even then patience is the key.

YOu didn't specify, but when you replied indicating that you wanted to set up an appointment, did you also include the information she asked you for?

Sounds to me that you did not reply with the inforation she had requested.

When that happens it is unlikely to hear back, unless you e mail with the information.

Lina

...she's cutting her losses by not replying to you.

Keep at it - be persistent.  And be nice.  Look at her site and supply all the informational accouterments that she requires. Then be patient.  Ping her back a couple days later. If you wimp out early, you will tell her you weren't really serious about her in the first place.  Plus, we're guys, we don't wimp out easily.  You have to balance being a nag with being persistent.

Different ladies have different requirements.  Follow her instructions to a "T".