Sexting rules

Hey ladies, i was wondering for those who have a sexting partner. How did you have the 'ground rules' conversation? It happened by mistake and included lots of alcohol; our friendship has this rly high sexual tension. We live different states and have know each other for 10 yrs or more. I did apologies to him incase i over stepped a boundary but he said he enjoyed himself and he'd like to hear from me more. How do i say that this is great and im rly into it but we need some rules??? Muchly appriciated ❤