Use Levels instead of Brightness/ Contrast:

Brightness and Contrast are what we all started out as thinking is the way to go.. but once you discover "Levels" you realize there's a new way to go about it.

Let's start with this photo I took under hazy weather.

Let's first try Brightness/Contrast to fix:
(click Image>Adjustments>Brightness/Contrast)

This just kindof darkens the whole image.

Now let's use Levels to fix:
(click Image>Adjustments>Brightness/Contrast)

Then drag the very left ticker to the right and the very right ticker to the left a bit as seen here.

Then POOF! Awww Yeah!

The Darks stay dark, but the brights get brighter!!

This is not the only way to use levels.. sometimes with a dark image you may start your tweaking by moving the middle slider a bit for the results you may be looking for.

This is the best method for over or under-exposed image correction!