I find these two videos by sargefaria helpful. My son watches them when we practice our knots.
In terms of great knot sites,
I found
http://www.animatedknots.com very useful. Its good for both left and right handed users. It has a commentary on what are the advantages of one knot over another for any particular situation. It also has recommendations when NOT to use the knot.
As for a short list of notable knots that form a list of useful knots to know how to use, I find
http://notableknotindex.webs.com very useful.
Thanks.
Conway Yee