This is a VST (Very small tip) :).
How to run xterm with white letters on a black background, opposite to the default black on white.
This should (IMHO) increase the duration of your laptop battery as less bright is used.
xterm -ls -fg white -bg black
You can create an alias for this command, like this:
alias xtermblack="xterm -ls -fg white -bg black"
And add that line to your
.bashrc file, so it can be set each time you boot up your computer.