Command completion: pressing <TAB> when issuing a command will complete the command line for you. Example: you have to type less this_is_a_long_name; typing in less thi<TAB> will suffice. (If you have other files that start with the same characters, supply enough characters to resolve any ambiguity.)
Back-scrolling: pressing SHIFT--PAG UP (the grey key) allows you to backscroll a few pages, depending on your PC's video memory.
Resetting the screen: if you happen to more or cat a binary file, your screen may end up full of garbage. To fix things, blind type reset or this sequence of characters: echo CTRL-V ESC c RETURN.
Pasting text: in console, see below; in X, click and drag to select the text in an xterm window, then click the middle button (or the two buttons together if you have a two-button mouse) to paste.
Using the mouse: ask your sysadm to install gpm, a mouse driver for the console. Click and drag to select text, then right click to paste the selected text. It works across different VCs.