Cropping- It is very useful when it comes to taking out things you do not want in your picture also good if you want to resize the image you are editing.
Wand Tool- Makes editing a lot easier, instead of erasing the background using the erasing tool which takes a lot longer you can use the Wand Tool, the wand tool selects sections of an image and you can delete it in one click.
Graduated Filter- It is simple to use and makes the image look better. I found myself using it a lot to make images look more clear and sharper.
Lasso Tool- Is like the Wand Tool but just as usefull depending on what you are trying to edit.
Text Tool- Not like the text tool in other softwares, it is a lot more useful and there are many features and ways to edit text and add text to images.