There are two facets of research: 1. internal
research where you evaluate how you feel, your behaviors, your instincts, your shifts, etc. and 2. external
research where you take #1 and apply it to existing animals and study them to see if your #1 actually matches up with them. For example, if you assume you're a wolf based on the fact that you like to howl, but you don't actually know that many other canines howl too, then you might not really a wolf and need to do more #1 and #2.
My problem with people not doing #2 in addition to #1 is that's part of the reason we have so many wolf therians. I think many people see wolf and simply stop there because they're lazy and wolves are somehow "cool" and the poster animal for therianthropy.
Additionally, people know about wolves from an early age, but how many 8 year olds know what a singing dog is? And A LOT of mammals have overlapping characteristics and behaviors. It takes research #2 into the species itself to be able to determine that that's a coyote feeling versus a dog versus a fox. Clades of animals overlap, so research #2 is necessary if you want to narrow it down specifically.
So it's a combination of gut instinct/what feels "right" and then learning about the animal in question.