New artist in the building?

And then there's P for Pen tool, X for switching primary and secondary color, then D for Default colors (black primary, white secondary), and then the brackets for brush size ( [ for smaller, ] for larger), and then the number keys for setting opacity, and M for Marquee select, and L for Lasso select, and C for Crop, and tons more. I love all the keyboard shortcuts in Photoshop. Once you get all the shortcuts memorized, you can cut out a lot of menu time and focus on doing the art part of art instead of the tool-switching part and you don't lose the creative flow so easily.

Oh yeah, and the best part about Digital art in comparison to traditional art... LAYERS! I love layers. Do any changes on a new layer and you can toggle the visibility on and off to determine if it looks better or worse. Or use adjustment layers to change contrast/hue/anything, and then you don't have to worry about altering the original image and can just play around with options until you get something you like. Layers are freaking awesome.

Haha, Layers! Didn't see this post before, but now I did, so some tips on Layers to follow.

Label every layer, and use groups and subgroups. It's easy to lose track of layers when you start adding a bunch while trying to get the right look. I don't do a whole lot of drawings, I use PS for texture work for my 3D modeling, but the same kind of advice applies. When I'm doing a texture for a character, I start off by making groups for each important piece (like a group for a jacket/shirt, a group for lower body, a group for skin/face, etc), then make layers inside the groups and name them (e.g Face Base Color), and then add new layers on top of that, labeling as I create. Then group all the groups together (group, never merge! merging is bad unless you're just merging to save it as a jpeg/png but always leave a PSD with all layers intact in case of edits) into one main group and call that group Diffuse and then make new groups for Specular and Bump and Illumination or whatever else I need. In the case of traditional art, you won't have all the different kinds(Spec, bump, etc), but if you have multiple characters, keeping each one in their own group can be mighty handy. If you're doing a piece that's a battle between two characters, give each character their own group first, and then make the sub-groups inside those and create the new layers in those groups. It really helps to keep everything on its own layer and in its own group, make a group for background elements, a group for each character, and a group for foreground elements. Organization and naming is key when it comes to managing layers.

I actually learned a couple of things from your paragraph! Which is saying something because I'm taking a college class with some photoshop and only learned maybe one shortcut with it. xD

I didn't want to overload the thread with just shortcuts, but...

G is gradient, V is pointer (dragging things), T is text.

And if we want to get REALLY technical...

Ctrl U brings up hue/saturation adjustment
Ctrl Shift U desaturates the layer (makes it all grayscale)
Ctrl I inverts the layer
Ctrl Shift I inverses the selection (what's selected becomes what ISN'T and vice-versa)
Ctrl D is deselect (when using the want, lasso, or marquee)

And uh... I think that's all I tend to use a lot of.

Oh, and as for tips in the actual doing-of, gradients, soft brushes and clipping masks are your friend.

Yay for learning!

Also, I forgot to put my favorite keyboard shortcut, Ctrl+Shift+N for creating a new layer. How could I forget?

But yeah, aside from shortcuts. As was mentioned, soft brushes and masks are very useful. Oh, another shortcut, but not really mentioning it for the shortcut, anyway, F5 brings up the brush options. There's a whole lot of options for brushes and you can get some pretty awesome effects from just the standard brushes. And then there's also a few websites out there with free brush packs that you can download and do even more crazy stuff with.

I think mostly all of my other PS knowledge is only helpful for making textures for 3d models, so I won't bore you with that info (but if you ever find yourself needing to make a tileable texture, Offset is awesome).