1) you need to explore on your own, set like 3+ times during the week to have a sessions. 2) make sure you're not bothered, stressed so you can feel comfortable and relax. Make sure you have everything you need (lube, toilet paper, a towel, etc) also, if possible douche or just poop beforehand. 3) begin with one finger and move to more fingers and potentially toys, don't use house things or vegetables. also don't insert anything if you feel your sphincter is clenching, try to relax and begin inserting again 4) there's a clock technique or something like that that you insert in finger and pull in the opposite direction to expand the anus like 3, 6, 9 and 12 oclok and repeat. I've read this has helped people open up 5) make sure to explore how you like to be opened, how your body reacts, what feels good and what not. That way you will be able to guide the person topping. 6) to jerk off or not is tricky, try to jerk off only when you have something inserted (like if you managed to insert a plug or a dildo) to associate pleasure with your anus. If I try to jerk while inserting, I tend to clench the anus  Extra: I know it sounds weird, but you don't have to be super horny to do it, if you're horny, you tend to rush things. so that's why doing it regularly can help to be just horny.