Essential Knots that we have learned in class so far:
Perfection Loop- This is a strong, effective and reliable knot! Great for tying a loop at the end of your line; remember that a lot of leaders don't have loops already tied on them! I like to use this knot to tie on streamers and hoppers, as it gives them a little more action. How-to video by Orvis can be found here.
Surgeon's Knot- This knot is probably the most effective way of tying two pieces of line together. One of the easier knots to tie, this knot excels when you need to tie two pieces of different diameter line together. I always do a triple surgeon's knot, because why not? It makes it stronger than a double! How-to video by Take Me Fishing can be found here.
Improved Clinch Knot- This is a quick and easy knot to tie, and probably the most popular choice of knot to tie a line to a fly for fresh water fly fishermen. How-to video by Take Me Fishing can be found here.
Orvis Knot-- this is my first choice of knot to tie a fly on to my tippet, because it is strong, tight and very small and light. I also believe it to be stronger than an improved clinch knot.
REMEMBER- The most effective knot is a well-tied one! Take your time and don't rush it!
Great article on knots by Art Scheck for MidCurrent, worth reading!