Decreasing

An decrease is a way of diminishing the number of stitches on the needle.

When decreasing evenly on both sides of a piece, as in a sleeve increase, it is important to work the decreases inward from the edges of the knitting in two different rows.

For paired decreases on either side of a piece, as with a sleeve, an easy rule of thumb is to work decreases on the right edge of a piece on a RS (right side) row, and work the decreases on the left edge of the piece on a WS (wrong side) row.

Most knitting patterns are written for the Western Knitting Method. Charts are wonderfully democratic references that allow all types of knitters to follow a pattern with success. I am very pro-chart.

Combination Knitting
Western Knitting
K2tog – Left Slant K2tog-L SSK or K2tog-TBL

Insert right needle into the leading edges of the next two sts together (starting with the stitch nearest the point) and knit these sts together. Slip next two stitches one at a time onto the right hand needle. Slip them back to the left hand needle one at a time, twisting themĀ  so the leading edge is facing the tip of the needle. Insert right needle into the leading edges of the next two sts together and knit these sts together.
Note: When the tip of the working (right) needle is pointing to the LEFT, the decrease will slant to the left.
In the above example stitches are mounted in Combination style
K2tog - Right Slant

K2tog-R K2tog
Slip next two stitches one at a time onto the right hand needle. Slip them back to the left hand needle one at a time, twisting them clockwise so the leading edge is facing away from the tip of the needle. Insert right needle into the leading edges of the next two sts together and knit these sts together. Insert right needle into the leading edges of the next two sts together (starting with the stitch farthest from the point) and knit these sts together.
Note: When the tip of the working (right) needle is pointing to the RIGHT, the decrease will slant to the right.

In the above example
stitches are mounted in Western style