Most images are not perfect SOOC (straight-out-of-camera) and could use a few tweaks. I am going to give you a few quick tips to lighten, darken, and/or "pop" your images easily and quickly in Photoshop or Photoshop Elements.
Lighten:

You took a lovely photo but it is too dark and you want a quick fix.

Ctrl-J your background (this makes a copy; you can also use Layer, Duplicate Layer). Then put this copied layer into Screen Blending mode and adjust the opacity to taste. This is a great method to brighten skin.
Darken:

Maybe you want to darken your image slightly.

Ctrl-J your background (or Layer, Duplicate Layer). Then put this copied layer into Multiply Blending mode and adjust the opacity to taste. This is a great way to burn in backgrounds.
Pop:

One really popular photo-enhancement is making your image "pop", which basically means you are adding more contrast. Here is a quick "pop" technique.

Ctrl-J your background (or Layer, Duplicate Layer). Then put this copied layer into Soft Light or Overlay blending mode and adjust the opacity to taste. Use Hard, Vivid, Linear, or Pin light if you are really adventurous. This is such a simple adjustment but the results can be quite stunning.
All of these adjustments can be used on color or B&W images. Easy isn't it! You can also combine the different effects (screen on one layer, soft light on a second), or use two of the same effects (if your image is really dark, make 2 copies, put each in screen, and adjust top layer's opacity to taste). Use layer masks to mask out the enhancements where needed (if you have PSE, download my PSE layer mask action). You can use a screen layer to brighten skin (mask out the rest of the image) and then a soft light layer on everything BUT the skin (mask out the skin). Play around with it! I used all three blending modes with layer masks on the after image below.

My next Editing 101 Tutorial will explain why you would want to use a S-curve adjustment layer, and include a free action for you PSE users who can't access Photoshop curves. Then I am going to have a tutorial covering Layer Masks and why you should love them! If there is a basic tutorial you would like to see me post here, please just comment below and I will try to add it to my list. :-)
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