I use this technique whenever a left-leaning decrease is required.
Slip 2 stitches individually as if to knit.
Insert left needle tip into the fronts of these 2 slipped stitches.
Knit the 2 slipped stitches together; 1 stitch decreased. To neaten this decrease on the next round or row, work this stitch through the back loop.
Here are two tricks to try:
Place your left needle into the front of the slipped sts and knit them together. This helps the ssk lie a little bit flatter.
If you want to go one step further to improve your ssk’s, try Trick Two which happens on the row/round following the ssk.
On the RS work a ssk, either the traditional way or as in Trick One.
In the following row/round: