Just couple rules to build on.
- Do not block caves!
- Try not to block large resource spots(Vocalno on Island is a prime example)
- Do not kill other people
- Do not drop wild dinos on peoples structures, dinosaurs
- Be nice to others and you will see that they will be nice back
- It is OK to demolish structures that are demolishable, if possible take the whole base instead of just looting it though. And try to ask before you do so, some people might just be away for holiday or such.
Now rules are here to be broken so:
Community builds are a possibility, so if you want to build a safe spot around cave entrance and leave it open for everybody to use feel free to do so, after you ask and get a confirmation that it is ok.
If you want to do a sparing match where you fight and might kill each other by accident that is OK as long as it is in friendly manner and both parties agree.
If you wish to discuss the rules feel free to do it on forums.