I am a curious man who is ready to have sex with another man for the first time, I would be a bottom I believe. Just want advice on what to expect or what I should do for my first time.
The most important thing is to breathe, relax and enjoy. Many people freeze when they bottom for the first time and just rely on the top to find his way in and that's not going to work out well at all, especially if you haven't used plenty of good lube. Bottoming doesn't necessarily mean being completely passive either - sex is about two people coming together, not one person doing all the work. If you are bottoming it's a good idea to push out (as though you are taking a bowel movement) at precisely the same time as the top is pressing his way in. Help your partner out! If you do this and you have lubed up really well, you should feel no pain or discomfort. Maybe experiment a little with sex toys first. If it's your first time make sure the top goes slowly and carefully because your ass is not a punchbag that needs pounding. If you feel comfortable at a certain point you can invite your partner to increase the tempo, but stay in control and use more lube if/when necessary. It goes without saying that you should practice safe sex. No condom, no play! Hope this helps.
My main advice is to find a top that knows what he is doing. By that I mean tell him this is your first time so he knows he has to help guide you, be patient and go very slowly. A top that just wants to stick it in and get it over with is a crappy top for the first time. I myself had a crappy ass 2-3 first times. We were both young and we had nooo idea what we were doing, so it took us a couple of times to get it right, which is also okay! Learning is part of the experience so enjoy it as well. One tip is that you can be the one riding them. That way you are in control of how fast and deep it goes. Squatting a bit also helps out.
I've bottomed twice (been a top before). First time didn't like it, and I told him to just pull out. Second time with another guy, after relaxing quite a bit more, a lot of lube and a lot of foreplay, it was amazing Just relax, and take it slowly at first.