If you want to get a reply, compliment her personality, her interests, her photos, or the fact that you have a lot in common.
Use your imagination, but remember to be on your best behaviour in a first message.
It's actually something that I talk about in great detail.
One of the biggest problems people have when they start learning how to sext and start sending them to their partner is that they go overboard with them.
It is certainly more exciting to see strongly overt orgasmic convulsions with lots of moaning.