There's many ways to increase your stitch count in knitting. Here are the most common techniques:
M1L (make one left)
A left leaning increase stitch. It's a very common technique because it's almost invisible.
M1R (make one right)
A right leaning increase stitch.
Kfb (knit front and back)
Knit into the front leg and then the back leg of one stitch. This can tend to leave a small hole in your work, but is quick and easy to do. If you're doing it near a neckline, then any hole will be hidden when you pick up neckline stitches later.
It's as simple as wrapping the yarn around your right needle as shown in the video below. Some online tutorials teach you to work a knit stitch immediately afterwards as if it was part of the Yarn Over itself. To clarify, that knit stitch should count as your next stitch. So if the pattern says "yo, k2", you'll wrap the yarn around your right needle as shown in the video below and if you move straight into a knit stitch, you'll only have one more knit stitch to work after that. I wanted to keep things more simple here and just show you the yarn over itself to save any confusion.