A few helpful hints:
When in doubt, Google it! I found most of my answers by typing in a few key words in the Google search engine.
Compile often! Don't wait until the very end to compile. You may have an error at the very beginning of the document, and it is much more difficult to try to find the error (or remember what the error could have been) once you have gone past it.
To crop a pdf document:
In Adobe Acrobat Professional 8.1, first make sure your advanced toolbar is open by clicking on Tools at the top, then Customize Toolbars. Make sure there is a check-mark in the box beside Advanced Editing Toolbar. Click OK.
Then there should be an icon that looks like two intersecting right angles with a diagonal line through them. Click on it. Next, outline the area in the image you want to keep. Click on the icon again and a box will appear. You can adjust the margins if you didn't get the box in the exact position you wanted. Click OK. If it does not look right, Ctrl-Z will undo your changes and you can try again.