Here are some tricks I use to make the edited pictures better. These are mostly filters that you can use that photoshop provides you with.
Image >> Adjustments >> Brightness/Contrast
brightness: -50
contrast: 50
Image >> Adjustments >> Saturation/Vibrance
saturation: 20
vibrace: -20
Image >> Adjustments >> Exposure
exposure: +1.01
offset: -0.5000
gamma: 0.69