There is no science as far as the factors affecting bitcoin's price.  I'm not an expert in economics of finance by any means, but I have observed that bitcoin is very sensitive to rumors and bad news.  Good news like when Overstock.com started accepting it tends to get absorbed pretty quickly, but negative events (or the possibility thereof) and uncertainty definitely play a role.

As of right now I cannot figure out why bitcoin has dropped so drastically in the past couple of months, since there hasn't been any bad or even lukewarm news to account for it.  People just seem to have got their fill of it and we're in a lull.  So if you are looking for factors to analyze, I would say keep your finger on the pulse of how people are feeling about cryptocurrencies in general.  There doesn't seem to be much else to look at.
That seems to be the majority of what accounts for price fluctuations.