Tips on how to sext!!!

I’m always scared to sext my fiancé!! I want to but I feel like I just can’t because I’m too shy! I am not just talking about pictures I mean texting something dirty! When he does it to me I love it but then I don’t know what to send back or I will send something lame. He is very cute and creative with it!! Then there is me lol. What are your tips???!!!!