A common post-production question involves Opacity and Fill, and what the differences are between them when it comes to photography. In this 14-minute video, Marc Newton from The School of Photography explains what sets them apart and how properly using them can dramatically improve your images.
PiXimperfect is an excellent resource for learning Photoshop techniques and in this 10-minute video, host Unmesh Dinda shows you how to add believable-looking snow to any image using Adobe Photoshop.
We're always looking to up our Photoshop game, but the lists of Must Know "techniques" or "skills" or "tools" we run across typically disappoint us by being either to basic or too niche. This useful Top 10 by Nate Dodson of Tutvid is an exception.