This module was VERY long, but there was a long of useful information. Best to keep everything organized in folders. I have a tendency to just plop everything down in a single folder.
The kernel density spatial analyst tool is very useful.. just remember that it uses your selection to create the density.
I never quite reliezed how easy it was to make graphs in ArcGIS. I am very used to making all sorts of graphs in Excel, but Arc is really just as easy!