Photoshop is an intricate and nuanced program, and as such, you can never have enough tips and tricks to make your work both easier and more efficient. This excellent and comprehensive video will show you 19 such tips and tricks for Photoshop.
Coming to you from Jesus Ramirez of the Photoshop Training Channel, this great video will show you 19 tips and tricks for making your life easier and adding capabilities when using Photoshop. Of them, my favorite is probably expanding the features and control of the Clone Tool (4:06 in the video). I already use the Clone Tool a ton for most of my work, and the first time I discovered these additional capabilities, I was quite impressed by how much they extended what I could get done with it. An additional tip that's helped me quite a bit is to change the size of the selection area when you're doing things like sampling colors. Photoshop typically defaults to a point sample size, meaning it's sampling a single pixel. If you're doing things like matching skin color, you can up with a bad selection if you click on a pore, a small blemish, or the like. Switch the sampling area to something like 5 by 5 average to make sure that you get the color you need.