Command Prompt: read this to know what to do when using tools; also use this space to search for commands by typing
Right Click Shortcuts: 1) Any time the command prompt tells you to press enter, you can right click instead. 2) If you want to repeat the command that you just finished, you can right click to immediately begin the command.
Canceling
a Command: Sometimes things won't seem to be working, because
you are in the middle of some command, and you don't know it. To
cancel the command, click the arrow button.Solid Tools: Some of these tools allow you to make shapes. Others allow you to add and subtract shapes. Some especially useful ones are union (adding shapes) and difference.
Ortho,
Osnap, and SmartTrack modes: these modes control how you
click, move, and locate objects on the screen. Ortho makes things
move straight up and down. Osnap gives you choices of what parts of
objects you would like to snap to. SmartTrack is hard to describe.
I would recommend turning SmartTrack off at first. 
Transform:
Allows you apply precise
geometric transformations to objects. You can move things
precisely, rotate things, and mirror things. You
can scale things in either 1, 2, or 3 dimensions. And much
more.Shifting your view: in Top, Front, or Side, right click and drag to shift your viewpoint. In Perspective, right click + drag rotates you around the object; right click + shift + drag shifts your viewpoint.
Changing your viewport: You can switch from the 4 viewport view by double-clicking the name of the view that you want (e.g. double-click the word perspective).
Changing
from wireframe to shaded (or some other view): Click the down
arrow (triangle) next to the viewport name, and select the mode that you
want
Unroll
Developable Surface: This takes all of the surfaces in
your object and lays them flat. It won't work for doubly curved
surfaces like spheres.Explode and Join: Explode breaks solids into individual surfaces so that you can delete some surfaces. Join welds them back together.
Extrude: Can make solids out of curves or surfaces.