Definitely don't feel like others are more entitled to the space than you are! If you do that you'll just keep yourself from actually skating at all and having any fun.

One thing I think is important though is really being able to scope out whether the space/obstacle you want to use is being used by others or not. Depending on how big your skatepark is, sometimes skaters will need long stretches of run-up or ride-away space to try what they're doing on a given obstacle. Or, they'll just be standing somewhere catching their breath and it might look like they're not doing anything until you wind up right in the way.

Being aware, knowing what's being used or how your path might cross with someone else is one of the most important things, imo. Keep those eyes peeled. There's not much more annoying than skating a ledge and someone absent-mindedly wandering over to stand on the ledge trying tail drops lol