I didn't take any classes. I just played with photoshop a lot. I use actions, but tweak the heck out of them. Playing with an action's layers can help you learn what different adjustments do to an image.
Try to get good exposure - I shoot RAW and tend to underexpose SOOC.. I fix it in RAW if needed and then edit in PS.
Remember composition, watch for limb chopping, get on the level of your subject.
For editing, make sure you defog your images (unsharp mask). That will sharpen your image. To fix blemishes, use a soft low opacity brush using the eyedropper tool to select the skintone .. or use the clone tool at low opacity.
If you're interested, I could send you a few helpful actions. PM your email if you want