FWB: What are the rules?

I am a late bloomer at ngayon lang ako nageexplore ng sarili ko sexually. I have this really good friend. He respects me and we value our friendship a lot. One horny day haha, biglang naging NSFW usapan at kaming dalawa tigang na tigang na talaga so pumasok sa isip namin maging FWB. Wala pang official na “Yes we will do it” so I am still playing with the idea kasi mga ante we have needs. 😭

My question is, how does it go? What are the rules na kailangan i consider? And if I am a softy, should I pursue it kahit alam ko may chance na ma-fall ako sa kanya?

Edit: I want to add na since wala ako masyado experience, maybe it can be a safe place for me to explore since he is someone that I know and trust.