Hi I only use the blood knot to attach backing to fly line. One of the best places to learn knots is at a web sit I know of it's www.clark-skamania-flyfishers.org
it has great tips for every aspect of fly fishing.
The other knots I use are the ducan loop, improved clinch, sergans loop (for leader to flyline), and the nail knot thats pretty much it. The web site I mentoned shows you hhow to do these knots step by step.
good luck and Tight lines!