To KICK START your machine knitting skills, it is very prudent to use your Knitting Machine, EVERY single day!
Practise a small skill. i.e hanging up a mock rib hem, short rowing a shoulder decrease, full fashioned decreases, seaming edges of various stitch patterning. Lots of small skills that add up quickly.
Those of us who took formal classes, we were assigned homework and needed to produce it for the next class.
Machine knitting requires experimentation. The yarn, the shape, the sizing, the type of stitches, which machine works best for the yarn etc. There is no one size fits all. If your goal is production type knitting, once these questions are answered, then go ahead and knit 100 sweaters, all the same. Keep in mind, changing the yarn type or colour of yarn, the garment will also change.
I can’t stress enough, the value of the info in the Manuals that are supplied with your knitting machine. Learn to make your machine go and then learn how to make things on it. They are TWO different skill sets.
Here is a cast-on that I find most useful, and a suggestion of a book for those who knit garments for ourselves or customers.