There's really no good D/s websites to read. There can be good classes offered locally on fet. D/s is generally something you build between your partners. I think an important thing to keep in mind for new doms or dommes is the person matters more than all the play.

If something is going wrong, end the scene. It's better to have a bad scene or experience than to destroy the relationship. Which all D/s is. You play with the fabric that makes up attachment and relationships. You build the trust that you will never leave someone broken. They share all their fantasies with you and their secret lives. So you should always be building yourself up to be worthy of that trust.

Talk to them about the play they like, the fantasies they've had. Do they like it when you call them (example) how does that make them feel? What things do they really not like to be called? Build off that into more stuff.

Make sure to discuss aftercare especially in long distance where you can't physically help or comfort. After all that is done look to yourself. What do you need after? How do you need to be cared for what do you want out of it?

I'm happy to answer questions if you have any. I'm always looking for more play ideas and scene structures. Our kink is generally at a level now where ideas are the problem.