GS's comment to go into things with an open mind and no agenda is good advice for almost any poly or potentially poly situation.
A question you might want to think about is why a poly relationship and a swinger relationship provoke different responses.
After a lifetime of mono programming, a common feeling is that emotional relationships are bad because a person has a finite amount of love within them. Therefore, any giving of love to another means a reduction of love for you. Basic poly thinking is that this is completely incorrect.
The example I use is two people who meet and marry. Do they love their parents less once they marry? If they have a child, do they reduce their mutual love in order to provide love to the child? Or is the capacity to love something that can grow?
While the capacity to love may increase, the hours in the day do not. Time management will be important. Worry more about time management than loving capacity.
Assume little; communicate lots. Best of luck.