The hardest part of digitizing is understanding how to interpret a design into stitches, such as why one uses a stitch type, why a certain stitch angle is preferable to another, how dense stitches should be to provide adequate coverage, and on and on. Add the functional questions about distortion, like how much wider should I make this element to compensate for pull distortion, how far outside the edge of this element should my outline be to account for push distortion, and it can get quite complicated.
These artistic and technical questions benefit greatly from experience. Though good educators can give you baseline settings and hints as to what shapes require a certain stitch type, or how you should sequence elements, the best way to internalize the nature of embroidery is first-hand experience. Behind a screen, you can forget that you are controlling a machine. Operating the machine makes your digitizing real. You feel the pain of errors, see the effect of your choices, and gain a clearer understanding of these complex interactions.