Editing takes time, quite often it takes a lot of time and many of the steps can be quite repetitive and boring. The best thing I've ever done for myself to speed up this process is memorizing keyboard shortcuts, so I've put together this list of five resources (in no particular order) that I've found to practice familiarity with these shortcuts and become more comfortable with the programs themselves. In order to cater to the largest audience I will be focusing on Adobe-tailored tools, however some may crossover into other programs.
5. Adobe's Online Shortcut List
This one's pretty obvious but some may not know it exists, Adobe's online help pages have a full list of every shortcut for every program they currently support. A large part of learning all of the shortcuts for me involved printing these out and coming up with memory games while editing images to remember them, which worked very well for me. Here's the Photoshop one, you can use the search to find others.
4. Keyboard Skins
If you're really dedicated to getting your shortcuts down as soon as possible, don't mind spending some cash, and have a Mac, Photojojo stocks some removable keyboard skins that overlay tool icons and names to your keyboard. This is available for Photoshop CS4-CS6, Lightroom 2-4 (presumably 5 as well), Final Cut Pro/Express, and Aperture 2&3. The same effect can probably be achieved with some clear vinyl stickers, a sharpie, and some patience if you're up for some DIY.
3. VSCO Keys (Lightroom)
The company known for their realistic "faux-film" Lightroom presets now offers a purchasable Lightroom Plug-In called Keys that allows the user to perform common functions with customizable keystrokes. It's not exactly cheap, but if a lot of your workload is within Lightroom, it will pay for itself with the time you save.
2. "Cheat Sheet Wallpapers"
A number of designers have put together various cheat sheets that can be set as a desktop wallpaper to quickly refer to. The guys over at Hongkait.com have a great selection for basic tool shortcuts here. You can also print them out instead, if you would prefer.
1. Trial and Error
For me, the quickest way to get a shortcut down is simply to jump into the program I'm using and start working, whenever I come across a tool that I don't know the shortcut for I hover the mouse over it (for most programs), get the shortcut then do it a couple times to commit it to memory. When it comes to using that tool again, I try the command that I think it's associated with, and if I'm wrong then I just repeat the process until I get it right the first time. I don't think I've ever had to do this more than three or four times before I had it down permanently, and now I can execute them without even thinking about what I have to press, similar to a musician playing music from memory.
If you have any other ways that you've found help you in memorizing shortcuts and increasing your editing efficiency, please feel free to share them in the comments!