Начать с изучения документации.Писать на чем удобно.Я предпочитаю C#.
Туториалы:
-
http://unity3d.com/support/resources/tutorials/
-http://www.youtube.com/user/cannedmushrooms#g/c/38D79E57A640D733
-http://www.3dbuzz.com/vbforum/content.php?176
-http://www.youtube.com/user/BurgZergArcade#p/c/2/O8-oZfi4utY
-http://www.youtube.com/watch?v=XxzkAqRBy9o&feature=related