Command line references

More extensive reference here.

Commands

Replace <file> with the path to / name of the file you want to act on

ls - list the contents of a directory
ls -al - show hidden files, long-form view
pwd - show path to current directory
cd <directory> - change directory
cp <from> <to> - copy
mv <from> <to> - move (also used to rename)
rm <file> - remove (delete) a file
rm -rf <directory> - really really delete (:warning:)
cat <file> - print contents of file to the terminal
less <file> - open up a paged reader for a file
subl <file> - open up a file in Sublime (assuming you've set up command line extensions)

~ is a shorthand for your home folder. It is typically the same as /Users/YourUserAccountName
. means the current directory; .. means the parent directory (one level up)
Directory paths can be given relative to your current location (e.g. cd code) or absolute (e.g. cd ~/code)
Press tab to autocomplete as much of the path as the shell can determine
Most commands take a --help or -h option to display a help page. Alternatively, man shows the manual page for a given command.
You should probably configure your prompt to at least show the current working directory at all times so that you know where you are (reference link needed).