In the instance of researching clan information online:
There is a lot of information out there, some of it will conflict, or not be thorough enough. The authoritative answers?
Your Clan's society I would say, talk to the clan convener, or perhaps the clan historian, or the High Commissioner for your area. Failing that, your heritage Clan Book would be a good source, at least one that is a recent printing: I have two Gordon clan books, one produced in the 50's or early 60's, and then one that has been produced in the early 80's, and while both are interesting, many of the names/septs that are in the later edition, are not in the older one, although the older one has more in depth clan history. Just an example of how information has been added to the small volume over time.
electricscotland is a decent source of information online as well... but that is going by online criteria only. It's great when backed up with more sources.