I guess the foundational questions to ask yourself before making this choice is why?
1. Are you sexually attracted to men? If so, then you can probably identify a particular guy that you find sexually attractive.
In which case, you might want to try a gay/bi male escort or go onto some App setting out your honest desires and what you want to find. Guys are fucking horn dogs and are promisicuous by nature. So you likely won't have any problem finding what you want.
2. Are you just interested in the pleasures of your ass and surrounding area?
If so, then start with SP's who rim. See if that is actually enjoyable.
If that turns your crank, try masturbating with a butt plug/aneros toy.
Then try MPA's known for good prostate massages with a simple hand job finish. See how that goes before going on to PM blowjobs.
Pegging could be the next thing if you find the anal (And mental) stimulation on its own, enjoyable.
Stop at any stage you are happy with.
Personally, I kind of wish I was bi and sexually attracted to men for the sole, single reason that it would open up wayyyyy more sexual opportunities.
But despite my love of being rimmed, of the intense orgasms of prostate massage enhanced hand jobs and blow jobs, Aneros enhanced intercourse with women, I simply don't find men sexually attractive in any way. I recognize why men would be considered sexy to women and other men, but it is just something that doesn't register with me. In fact, (please don't take this in any way to be homophobic/bashing etc) I find the idea of sex with men (or TV's) a turn off. I have been in countless threesomes (and moresomes!) when swords have been crossed (like DP's-one dick per hole-ie: one in the pink and one in the stink) and that doesn't bug me. But deliberate m2m sexual touching is unappealing to me.
So in my case, I'd love it if I had a girl rimming, stimulating my prostate or even pegging (not tried that yet) me while I am fucking another woman would be awesome. But if it were a guy's tongue, finger or dick... that would turn me right off instantly.
So... I guess you should drill down to find out exactly why and what your foundational desire is before you decide how and who with.