How do you find most effective keywords for your niche?

I have some content and would like to isolate both the most effective keywords for my niche that 1) generate the most traffic and 2) lower traffic keywords that are "long tail" (which for YouTube is a little different than normal SEO, but I want to find people looking for rather specific topics / information).

I use Keyword Researcher for long tail research for standard search, but what do you do on both of these counts for YouTube research?

I tend to like just using simple ol google keyword tool. That way when I show my customers who is tracking the views are from, they will believe it is a reputable source.

me too. google keyword tool and sometimes youtube keyword suggestions

google keywords

But if you're asking how to get different keywords for your main niche keyword, to see which one is the best, check this out:

http://ubersuggest.org/

You've probably seen it before. When you search for a keyword, you press the + signs to add it to your list, but if you click on the WORD, it will have a drop down of more words, where you can add those variants to your list. You can then click THOSE words, and keep going - it's a great way to stack keywords and get a whole bunch of varieties to compare all of the search terms.