One of the most common mistakes that photographers make is over-editing photos. I've seen great images taken, and then edited into oblivion with the photographer thinking they are actually making it better. So how do you avoid doing this if you don't even know you are doing it? Find a happy medium and use layers to make this work.
I realized the other day while I was editing that I had developed a new approach without even realizing it. I've used layers for a long time now to avoid ruining the initial image, but have now started using them to avoid overdoing any single adjustment as well. Here's how I do it.
First off, you'll want every adjustment to take place on it's own layer. This is easy if you use the adjustment layers panel for everything since it creates a new layer for each adjustment. But what if you want to apply an adjustment like LAB color mode to it's own layer?
Create a new layer by pressing CMD+J on a mac, and CTRL+J on a PC. Perform desired adjustment.
Now that you have a new layer with the adjustment, make sure the layer is selected, and adjust the percentage. At first you'll think, "I want it to stay at 100% because it looks great." This is almost never the best option though. Slide it all the way to 0% and see what you think now. Does 0% look good too because it contains more detail and maybe more or less contrast? Now slide it back to 100%, it might look overdone! This is where you find your happy medium, in your head you are thinking that it looks good at 100% and good at 0%. Going to 0% won't make a difference, so find a spot somewhere in the middle, maybe 50% or maybe 66%.
By dropping every adjustment down a little bit, your images will never come out over-processed. The problem with doing every adjustment to 100% is that once you have applied several changes, the image becomes unrealistic looking. Sliding each down helps control this and you'll soon realize that lots of smaller adjustments are more powerful and less destructive than several big ones!
This has changed my editing drastically and lets me perform more adjustments. Hopefully it helps you too!