You have a new-to-you yarn that you'd like to knit.
Where do you start?
The ball band may gave you some information about the suggested needles to use for hand knitting and what stitch gauge you might get, but as machine knitters, this doesn't tell us enough. For example, this information doesn't tell us what tension to turn use on the tension dial of the machine.
What do you like? How does the yarn look and feel in your selected stitch pattern?
Does your machine "like" this yarn? Machines can be fussy with some yarns
How is this yarn going to wash and wear? Will it shrink, fade, pill or bleed?
Knit a "get acquainted" (tension)swatch
Cast on and knit at various tensions.
Take time to play with your yarn.
Start at a tight tension and knit a few inches changing the tension as you knit. Marking the tension with eyelets as you go.
When you take the knitting from the machine, you'll get a good idea of what tension feels best to you and looks best after blocking.
Armed with that knowledge, you can establish your stitch and row gauge by knitting an accurate, "real" Gauge Swatch . No surprises here!
"Get Acquainted" with a yarn by knitting a tension swatch. Gradually change (and record) the tension to see how it feels and washes.