Composites and image manipulation course recommendation

Hi,

I'm looking for some advice. My Photoshop is pretty decent when it comes to retouching, and while I can happily put in overlays and stuff to enhance some outside pictures, I feel I have a lot to learn from this side still.

Can anyone recommend any decent course/workshop that is worth grabbing from this site as obviously there is a lot of choice, but would appreciate some feedback from those who have maybe watched any to find which ones are the better ones.

Many thanks.