Photoshop Tools you SHOULD KNOW BY NOW...

Rectangular Marquee Tool (M)
Use this tool to make selections on your image, in a rectangular shape. This changes the area of your image that is affected by other tools or actions to be within the defined shape. Holding the [Shift] key while dragging your selection, restricts the shape to a perfect square. Holding the [Alt] key while dragging sets the center of the rectangle to where your cursor started.

Move Tool (V)
Use this tool to, well, move things. Usually you use it to move a Layer around after it has been placed. Hold the [Shift] key to limit the movements to vertical/horizontal.

Polygon Lasso Tool (L)
Ok, this should be the Lasso Tool, but I use the Polygon Lasso a lot more often. Use this to draw selections in whatever shape you would like. To close the selection, either click on the beginning point (you’ll see the cursor change when you’re on it), or just double-click. When holding the [Ctrl] key, you’ll see the cursor change, and the next time you click, it will close your selection.

Magic Wand Tool (W)
Use this to select a color range. It will select the block of color, or transparency, based on wherever you click. In the Options Bar at the top, you can change the Tolerance to make your selections more/less precise.

Crop Tool (C)
The Crop Tool works similarly to the Rectangular Marquee tool (see above if you have no short-term memory). The difference is when you press the [Enter/Return] key, it crops your image to the size of the box. Any information that was on the outside of the box is now gone. Not permanently, you can still undo.

Clone Stamp Tool (S)
This is a very useful tool, if used wisely. Choose your brush size, then while holding down the alt/option key on the keyboard, click on the area you want to clone, release the alt/option key and now click and drag over the area you want to replaced. It’s a direct copy of the information from the first selected area to the second.

In addition to these tools you should be familiar with all corrections under IMAGE > ADJUSTMENTS to improve your images...