For me, defining Poly means defining a relationship.
-Each and every relationship I have is independent and should be defined independently of other relationships. Maybe I have one relationship that is very physically and emotionally involved, we spend a lot of time together, and are working toward a deeper commitment. Another relationship may have a very strong emotional aspect and a very small physical aspect, we spend much less time together, and have no desire to move the relationship to a level that has deep commitment.
Note: At some point I'm sure to talk about 'rules' but let me make a note here that this concept of independent relationships applies to the 'rules' in my relationships as well. I have very few 'rules' I insist upon for myself but often the relationships I have will include rules. They are not the same in each relationship but are instead defined within each relationship.
-My relationships may overlap and in fact, I hope they will. But it is never required that any of my loves are more than social acquaintances with each other. Nor is any kind of physical interaction ever required. (Sorry to disappoint those of you who thought being Poly meant lots of threesomes and orgies).
-Honesty. Always in all ways. I like to know about anything my loves are thinking or worrying about before it becomes a big problem. I am very clear from the beginning of a relationship that I can't live with dishonesty and will likely end the relationship if I find there has been dishonesty.
-Communication is extremely important. Again, this is something that I bring up at the beginning of a relationship as a requirement. I welcome any conversation and I also let potential loves know that any topic they need to discuss I will respond to in an adult matter, without judgment. And of course, I refer them to my needs regarding honesty.
-I firmly believe that everyone should have choices. Sooner or later in a relationship there will probably be a difference of opinion. Rather than try to fight with someone to change their mind I prefer to let them know how I may have to react to their choice, thereby letting them know how it may effect me. For example, if one of my loves tells me they are going to quit their job and move to another country. My response would be that I love them and I want them to do what is right for them. At the same time, what is right for me is not having long distance relationships. Should they move I will still love them, and miss them but, I wouldn't be able to continue the relationship in the same manner.
-And probably the biggest ideal I have about Polyamory is the freedom to explore relationships. Fundamentally, Poly for me is about having the freedom to entertain the possibility of a relationship with whomever I choose, whenever I choose. (No, sorry, this doesn't mean having sex with whomever, whenever). It is about not having to ask permission, seek approval, or be worried about reprisals from my existing loves. It is being able to explore different paths in life without doubting I will have support from the ones I love. That doesn't mean I don't consider my existing relationships when I encounter a new interest, only that my existing loves will know I did consider them and made the best choice I could. And they will realize I may make mistakes, as I realize they might as well.
P.S. This is one post I can see being changed or updated over time.