If you've never saved your user settings, then take two minutes to watch this quick tutorial by Darkfall. It'll save you a lot of time in your Blender career!
How many times have you deleted the default cube? or changed it from Blender Internal to Cycles? or countless other little changes?..
If you find yourself always making the same changes before you even get to start a scene, then you should consider optimizing your workflow. Make the adjustments once and then save your start up file and save yourself tons of time.
I know many of you may already know how to do this but I must admit, it took me a while (and the deletion of thousands of default cubes) before I optimized my workflow.