I thought I would do a post that I hope will make the m1l and m1r increases less confusing. I won't go into the details of "how" you make these increases because it can vary depending on your personal style of knitting and also weather or not you are a mirror knitter. This is pretty much the same post I put on Ravelry when someone was asking about these increases.
The M1L and M1R has to do with the direction you twist the bar. Generally you lift the bar between 2 stitches to make these increases. If there is a lot of twisting in the pattern, you can set them up on the row before so that you are not stealing yarn from the surrounding stitches. This is what I did on my "the drunken mason" scarf.
the difference between a M1L and M1R is the twist. on a M1L the leg in front will be slanted to
the left, on a M1R it will be slanted to the right. Generally these are used when stitches need to slant away from a particular line in the knitting so the top leg will slant away from what ever it is in the pattern you are increasing.
If you knit in a way that your leading leg is in front, for mirror knitter (knitters who move their new stitches onto the left needle) the M1R is the same thing as a KTBL. For standard (non mirror knitters) a M1L will be the same as a KTBL.
If your style of knitting results in your leading leg in back, you will want to slip the stitch to reposition it so you can knit through the back loop to get the twist.
So when you are required to make a M1R or M1L, twist your stitch as I show in this diagram. This is as though you were looking at the knit side of the fabric.
When working from a written pattern, a mirror knitter will want to switch these. If the pattern is telling you to make a M1R you will want to swap that for a M1L and the same goes for when the pattern tells you to make a M1l you will want to make a M1R. this is because we are approaching the stitches and knitting from the opposite way.
When a mirror knitter is working from a chart you will want to make the increase in the direction they tell you. But if they give you instructions for how to create the left and right stitch, you will want to swap the directions. The directions they give you for a M1R will result in creating a M1L, and vice-versa.
But in short, for both standard and mirror knitters, you simply want to twist your yarn so that your stitch looks like the loops in this diagram.