i'm polyamorous and both of my partners are monogamous - one by circumstance (he's just never really felt the need or desire to date anyone else since we've been together - we've been together 7 yrs) and one by choice/disposition (he never planned to date anyone polyamorous and has no interest in it, but we fell in love and he's been really accepting of it - we've been together 1 yr).
the things that have been most important for us are open and honest communication...c., my partner who defines himself as being monogamous, had never really been in a relationship where that had been encouraged before. and the other thing is addressing it when jealousy comes up. usually it's around the idea that he's not enough for me, or i might find someone else and want to leave him, etc. so we've had a lot of conversations about breaking down those ideas/fears.
i'd love to date someone who is also poly, but with a few exceptions, i have always ended up with monogamous people. and it's worked pretty well in my long term relationships