Use Photoshop to enhance your pictures, not to create your pictures.
Photoshop can be an awesome tool to improve the look of your photos, if you use it wisely. Try to avoid over-editing (i.g. making pictures too bright/dark or too contrasty, or adding tacky texts to pictures).
To create the good picture, I used this tutorial (via A Piece of Lisa) with one alteration: my Soft Light layer was set at 30% opacity instead of 80%. I then added a color fill layer (ffebc1 at 75%) to give it an Autumn color.
To create the bad picture, I used the Brightness/Contrast feature, with a lot of contrast and a little bit of brightness. Then, I used Hue/Saturation and increased the saturation significantly.
The good picture simply gives the picture a bit more contrast, as well as a somewhat warm feeling. It takes the picture, and brings it a step up.
The bad picture is simply bad because it is too bold. The white is extremely harsh, and the colors are too vibrant. It hurts the eyes of the viewer, and also shows that the editor increased the amount of color within the picture a bit too much. The original picture is a smidge dull, but the colors do not need to be adjusted quite so noticeably.
Keep in mind that these are tips for photos that are to intended to be used for blogging. If you edit these pictures for your own viewing pleasure or for artistic reasons, then you may wish to have an overly vibrant picture. As for the blogging world, however, harsh/bold pictures are not usually appreciated.