First off:
Do not attack people directly. What I mean is, don't make a story just to make fun of someone or a group of people. We are all here to have fun, so don't ruin it for somebody else. Same goes for the chatbox. Also, if you know something about you may upset others, try and keep it to yourself. You have been warned.
Second:
Try to make sense. If we are in space and then someone makes a car for the purpose of travelling faster, that makes no sense. Try to keep things simple, don't try to do too many things at once. Otherwise, people will either get confused, or get angry at not wanting to do what they wanted to do.
Third:
Let the later posts be changed. If you make a post that conflicts with another one, let the person whose post comes later edit theirs. Otherwise, the story becomes muddled and confused and no-one can do anything.