Well done darky. You did better than I did (http://www.recreationalflying.com/forum/general-discussion/54754-interestin-incident-share-especially-those-without-much-experience.html)
Something I've noticed is that when people are preparing to line up, they are not looking the direction that aircraft are coming from, ie they are pointing down the strip and can't see what's coming. I always stop looking at approaching aircraft, then when I hear that it's free and SEE that it's free I enter the runway.
I guess the same rules apply in the air as the roads, don't trust anyone else.