Longboarding Basics - StandingNext, try standing on the longboard. Get a feel for the longboard's springiness. Bend your knees and crouch down, then stand back up. Get used to shuffling and moving your feet around to different spots on the longboard, without stepping off of it. Basically, get comfortable on your longboard!
Longboarding Basics - Foot PlacementFor longboard foot placement, it depends on what you are doing. Most of the time though, I keep my feet between the trucks at a little wider than shoulder width, with my front foot pointed diagonally out at about a 45 degree angle, and my back foot pointed out slightly (not pointed directly forward, but out a few degrees). There's an excellent chance that after riding for a while, you may find a more comfortable stance that works for you.
For bombing hills (longboarding down hills fast), I like my feet spread wider. If I want more speed, I like to point my feet ever more downhill. It's also important to put a good amount of weight on the front foot when hill bombing, to remain in control. Or in as much control as is actually possible!