I've made two of these furry crocheted muffs now, so I think I can walk you through it.
yarns: one chunky velour or chenille yarn; two strands eyelash yarn
hook: size H (or whatever size gives you a fairly tight fit to the thickness of yarns you have)
other: two large beads with hole big enough for a crocheted chain of your yarns to pass through
1. Holding all three strands together and using a fairly small hook, make a chain approximately 11 inches long. Now test it out. See if you would like the opening to the finished piece to be larger or smaller.
Tip: If you intend to line it with fabric or put a pocket inside or something, you need a slightly larger length of chain.
2. Join last chain to the first chain with a slip stitch, forming a loop.
3. Single crochet in each stitch of the chain in the loop, marking the first stitch and joining the last sc to the first sc with a slip stitch.
Tip: Count how many stitches you have (this is handy because with these fuzzy eyelash yarns, it's easy to lose your place, skip stitches, add stitches, etc; marking the first stitch of each round and counting the number of stitches saves the hassle later of finding your work is expanding or shrinking hideously).
4. Check the size of the loop again and be sure you like it (I do not like unraveling three strands of fuzzy yarn worked together because I end up with a horrible tangly mess; better to check now than decide you hate it ten rows down the line).
5. Repeat step three until muff is desired length (or eyelash runs out -- in my case, the eyelash yarns always run out at about the right length of muff if I start with the usual 50g balls).
The black muff in the picture is about 6" wide and 10" long (and will be lined, etc., so it's a bit roomy).
6. Make a wrist strap: Make a chain approximately 15-16 inches long. Thread one of the beads onto the chain, leaving it somewhere in the middle of the chain. Double the chain over. Thread the second bead onto BOTH ends of the chain and sew the loose ends to the muff on one end. The bead with both sides of the chain running through it should slide up and down the wrist strap to tighten it and loosen it, while the other should keep the sliding bead from ever being able to escape.
I made one out of two strands of white Kitten mohair and two strands of Schachenmayer Brazilia and found that with those yarns, the little holes between and around stitches showed a lot more than in the black one that was made made with a thick velour-type yarn and two eyelashes. The black one came out so dense that I actually tested a piece of red fleece on the inside as a lining and it didn't show through. The white one was a different story. I'll absolutely have to line it, if I want it to be warm (I haven't done that yet) and decided to decorate it.
I have basically no embroidery supplies and even fewer skills, so I just took some brown crochet thread and a needle and sewed some rough branches onto the outside of the muff. Turns out embroidering on eyelash is kind of a pain, but the results don't look too bad. Then I used some Japanese mohair in a pink orchid color to put little buds on some of the branches and attached three 3-D crochet flowers to the branches in a couple of other places. The effect is sort of like those cherry blossom paintings (or it was supposed to be).
I made the flowers like this:
1. ch 4; join with sl st to form a ring
2. ch 1; sc 10 times in ring; sl st to beginning ch
3. (ch 2; sk 1 sc; sl st in next sc) around, which should give you five little ch-2 loops
4. sl st into the first ch-2 loop; ch 2 and then 4 dc in the loop; ch 2 and sl st in the same loop to finish the petal; sl st into next ch-2 loop and repeat procedure.
5. Can you find the skipped sc back in step three? It should be at the bottom center of each of the five petals you've just made. You want to sl st into the back loop of that skipped sc (or frankly, poke into anything in roughly the right spot and the flower won't be too warped) then ch 3, and sl st in the next skipped sc. You should end up with five loops again, just as in step 3, except they will be ch-3 loops.
6. sl st into the first ch-3 loop; ch 2 and then 7 dc in the loop; ch 2 and sl st in the same loop to finish the petal; sl st into next ch-3 loop and repeat procedure. Finish off and weave in ends.