For the tips, I'd like to add something. Suppose that for some reason, you'd like to restart the game but keep your control settings (and maybe binds, if you have 'em). Go into the console, and type the following:
hud_health_green 0
This will set your campaign progress back to only Cutman's stage being available. In other words, back to the start.
In my case, I wanted to restart because I'd like to see every thing Dr. Light says during the campaign as I don't remember.