One of the best embroidery stitches to learn, especially as a beginner, is seed stitch.
This is one of my favorite stitches to teach new embroiderers because you can use it without a pattern. Choose a few colors, thread a needle, and you can start practicing.
This is the most basic up and down stitch. You come up at one point (A) and go down about 1/8 inch away(B). Then you start your next stitch about 1/8 to 1/4 inch away(C). I don’t like going further than 1/2 inch away on any of my stitching because there is a bigger chance of puckering fabric or the thread getting caught on something.
For you visual learners, here is a photo tutorial and some tips.
Filling an entire hoop with different color seed stitches is very relaxing and you end up with a beautiful piece of abstract art in a hoop.