ORIENTATION & GLOSSARY FOR THESE DIRECTIONS
Neutral Position (see 1st picture below): Turn the needles and place them into your left hand, tips pointing to the right.
Round: all the way around both needles.
Row: used in the heel directions, when you’re only working back and forth on one needle.
VISUALIZING THE MAGIC LOOP SET-UP
If you've never used the Magic Loop technique before, it might help to understand how to visualize it in-action before you cast on. (If you have used Magic Loop before, skip to Part 4.)
Start by conceptualizing the set-up for your socks. Envision the cable needle lying on a table, folded in half, with the ends pointing right and the fold at left. The two halves are parallel to each other, with one just above the other. The total number of stitches for each sock are divided so each needle carries half the stitches. (When you're knitting socks from the toe-up, this division is generally made so all the top (instep) stitches are on one needle and all the bottom (sole) stitches on the other.)
Sock 1 will be on the right and Sock 2 will be on the left. The stitches for the top of the foot will be on the lower needle; the stitches for the sole of the foot will be on the top needle. A good, healthy amount of cable loop juts out on the far left, dividing the 2 tops from the 2 soles. Each sock is attached to its own skein of yarn, which is attached at the right side of each sock on the **upper** needle.
As you work your way around the sock, you do the following (basic process of magic loop knitting):
At the beginning of each sock edge, always check the position of your working yarn before making the first stitch.
However, you don't want to pull it so far that you lose the extra fold of cable dividing the instep/top stitches from the sole/bottom stitches.
I DO THIS FUNKY THING WITH MY HAND (A TIP FOR YOUR GRIP)
... so you don't inadvertently create an extra stitch when you wrap the yarn for your first knit stitch. You want it to look like this:
If (when your first stitch is going to be a knit stitch) your yarn is coming in like this...
... you are going to end up with a YO between the two needles (i.e. an extra stitch) that doesn't belong there.
While it's not the end of the world—it will not create a problem in the knitting and you can extract it the next time you work around—it can be a real pain to deal with.
I've found that when I'm knitting two socks at once on magic loop, I hold the needles normally for Sock 1...
...but I change my hand position for Sock 2: I put my hand through the cable...
... then fold it down...
... like this ...
... so the area between my thumb and forefinger pushes up against the work. It's a more comfortable grip and helps me control the work better. Plus, I like how it feels!
HELP FOR THOSE TIMES YOU PUT DOWN YOUR WORK
When you've put down your work and forgotten where you left off, how can you can figure out where to start knitting again? There's no possibility to get it wrong if you stopped at the end of a row or round. But what about those times when you're forced to stop mid-way on a row, between the two socks?
Start by looking at your work. By now, you know that your working yarn needs to come from the right side of the knitted section farthest away from you. However, there are two possible ways to hold the work and still have the working yarn coming from the right side of the knitted section farthest away from you. So which of the following two pictures shows the proper orientation to begin knitting again?
Did you really even need me to confirm that it's Picture A? I bet not!
Why is Picture A the correct answer? Because your working yarn always lands at the end of the side you just finished, so it will be on the cable side when you're ready to knit the next side off the needles. Picture B would have you either (a) knitting back into the stitch just knit or (b) trying to knit the first stitch on the cable—which you'd never do (or admit having tried) because it would involve crossing your needle over the cable... and even if you temporarily lost your mind and knit the first stitch that way, you wouldn't be able to pull it off to knit the next stitch!
So always orient your work with the needles closer to you and the cables farther away. Only one of the two working yarns will be in the right place for beginning.