These are basic editing skills you will need to make you photos look amazing!
Levels, Brightness and Saturation.
Levels. When you open the levels window (in PS, image > adjustments > levels), you will notice that there are little "mountains", and arrows in each corner. You have to move those arrows towards the end of the mountains, and that is it!
Brightness (in PS, image > adjustments > brightness). You have to be really careful
not to add too much brightness, because your image will loose quality and start looking noisy.
Agus has become such a help to me, when I'm in a tough situation, that is when it comes to editing. And you'll have to go on the page to read about the saturation. But the side by side comparisons really help in that before and after effect.