Before Season 3 airs...

What is the best episodes to watch of Seasons 1-2? Like out of the whole number of episodes, what are the ones that you can watch out of the rest you can ignored?

I found this article concerning, but are they right?
http://ift.tt/2aVT9nL

But for both seasons, 1 & 2, what are the ones you can watch only before Season 3 airs?

Before Season 3 airs...