One possible solution: presets. Most programs with which you process your pictures have presets that give your photos a certain look with one click. Just like the presets in your camera which can make your pictures extra vivid or sharp or full of contrast from the onset, post-processing presets - which you can also create yourself - provide you with time-saving steps for giving a group of pictures similar properties. For example, if you are planning to show a half-dozen pictures together, you may want them to share a similar color spectrum. Smart phones have apps that give the photos a blurry green, artsy-retro look. I'm sure you've seen them on Facebook. I am not sure why blurry green pictures are supposed to look artistic, but then there's a lot I don't understand.
Back to presets: In Adobe Lightroom or Photoshop or many other photo processing programs, there are presets available for free on the web or in magazines and they are fun to try out when you have a series of pictures you want to play around with. I even had one of mine published in the Dec. 2010 issue of Digital Photo. However, I believe the real art comes when you have your own vision and create presets for your pictures yourself.
These last two pictures below have very similar contents and yet each one has a fairly different feel to it. Can you put your finger on what the differences are? Which one do you prefer? Why?