How close should the nozzle be to the substrate? I have my nozzle close to the substrate that I am printing on, so that a piece of paper can just about slide underneath it freely, without catching.

Is this the right way to do it?
This photo isn't exact, but may help

Edit: Whoops! Forgot to include source. This is from the Wanhao User Manual/Build Guide. I can't quite find the webpage at the moment.