Can you give me some pointers on writing a persuasive ad? Thank you!

Hi all,

I am advertising my services in a Facebook group as I've got some business from it. It's mostly text and a picture. What are some persuasive ideas, words, or thoughts I could get people to reach out to me more? How can I be more intriguing? I'm in a bit of a slump lately so I'm trying to always improve and change it up. Thank you so much.