Someone once told me that if you can tie a good muddler, you can tie just about any pattern ever made. I think that's probably a fair statement. There's a bunch of different tying skills needed to tie one - spun deer hair head, matched quill wings, tinsel bodies - many skills & techniques that apply to many different flies. The muddler is difficult because it has all of these on one fly.
As far as fishing the muddler, it's my go-to fly for many warm water fish like small mouth bass & crappie. I've also used it to imitate not only sculpin, but also used smaller muddlers to imitate large nymphs & whatever else creeps & crawls along the bottom. For me though, the muddler is most impressive at night. The deer hair head really makes some noise cutting through the water & gets plenty of attention from those big monster fish that come out in the dark.
So, I'll keep working on my muddler tying skills. A good place for me to start is this video below. There's a lot of cool tricks in this video that will help in other patterns as well. It's a few minutes long, but then again tieing a good muddler takes a few minuets.
The muddler minnow is a great pattern to add to your fly box & can be a fun challenge to tie.