Take it from a gay man...

When I was younger, I sat on the guy the first time, I orgasmed, with one touch.A lot of guys tense up, which makes it worse.You should use a water bottle and make sure you are clean inside. It is much better if you push,like when you have a bowel movement.It relaxes the sphincter muscle, when you tense up,it tightens the muscle which will cause pain until you relax. Being on top and controling how fast you are penatrated, always helped. You can always change to another position once you are ok with it. Lying in a sling is good,but you loose control of entry. I usually top, there is more guys that want to bottom. Some guys never bottom,thinking it is not masculine. Also tops are in control, which leaves the bottom at your mercy/ Start with someone you trust.