I've had to change a lot of my expectations as to what is the relationship between amount and frequency of communication and level of interest. Like, there was a time when I used to have weird rules like 'If they answer your questions but never ask you anything back, they're probably not interested' or 'If they don't respond in one day, their interest is waning' etc. Then out of the blue a message comes, and I am left
as to 'I thought they weren't into me'.
I don't have a lot of experience in mono dating, but isn't the expectation usually that while seeking out a primary partner (I guess for monos it's just 'partner'), you tend to play the field, go on dates with several people at a time and see where it goes? That also requires dividing up your time and attention. But I think at least nycindie's blog details some of the joys and tribulations of single poly woman dating, and doing a general tag search on 'dating' might give some cool ideas, too.
I have been toying with the idea of where is my limit as to how many partners I can even theoretically fit into my life, time and energy wise. Some people use the primary/secondary/tertiary distinction, and I've been wondering whether it would a useful temporary paradigm for my relationships as well. Thus some relationships would have less expectations in what comes to meeting regularly or having continuously increasing intimacy or planning a future together. But then again, I'm really allergic to any kind of expectations in early stages of a relationship.
I would discuss the other person's other relationships, and their hopes and expectations in what comes to them. That could potentially help to gauge what kind of 'place' in their life they would have for me. Some people are really upfront about what they are looking for. And asking questions is really in the heart of poly in so many ways, because like you pointed out, there are so little models on what works. Which is something that attracts a lot of people to poly, come to think of it. You get to make your own rules.