Tons of lube. If you think you have too much, use more still. Do not use any lubricant that contains lidocaine. Do not use poppers, drugs or alcohol. Do not play with people you don't trust to have your well being at heart. An abusive partner will not care about damaging you. Don't ignore pain. Don't feel pressure or haste.
Don't be naively influenced by porn. Ava devine may look sexy in her videos, but she isnt capable of bowel movements off screen. That sounds fun until you're trying to discreetly enema on a 10 minute break at work.
Use proper toys, constructed from proper materials. Never use bottles with labels or sharp edges. The small seam on a label can shred your ass, opening you up for infection. Never use vegetables. Plastics, pesticides, etcetera do not belong inside us. Anal cancer is real and terrifying.
Never use anything that can become stuck inside you. An er team will do extraordinary damages just trying to remove even a small object from your ass. You literally have to shove your arm in someone with forceps to retrieve an object. Or worse still, perform surgery on the abdomen. It's horrific.
It's just common sense stuff but you have to be safe. Once you get a serious problem, that's it. No more anal play for you. Ever. If you have passion for this hobby, that could be devastating. Or you could hurt someone you love.
The most important advice I can give is to make sure your prolapse goes fully back inside after play. A prolapse trapped outside your rectum can be pinched and starved. The tissue will die and you may die as well. This is very important. If you cannot get your prolapse back inside, call an ambulance immediately.
Also, never use glass! I used to peruse the efukt forums. The man who made the video called 'one guy, one glass' was also a member. His experience with broken glass was terrible. That video was a joke and a meme to most of the internet but that man had to live with what he did to himself.
Just be smart my friends. We are all influenced by porn but there is a lot going on off screen. We have to keep reality in mind. You will make some proctologist very happy, with an enormous bill and a dangerous, life altering surgery. If you aren't smart. But then again, there are medical professionals much smarter and more experienced than me that will say the only safe way is to not engage in extreme play.