Ok, I've never had contents insurance (no need to worry about home and contents as we are renting). SO I don't really know what to look for...

I guess the obvious theft, fire, storm, flood which are the big 4 that scare me the most but...

Is there any 'tricks' an insurer has that might ever stop a claim? Do I need receipts for everything? Should I take photos? How do I keep them safe in a fire or somethig like that?

What generally stops a claim from going through? I don't want to ever be in a position where I THOUGHT I had contents but then find out after any event that I should have done xyz and so I'm not actually covered...?

Yes the floods and fire are scaring the crap out of me. Plus I think its a good thing to have anyway. But mostly the recent floods and fire, and losing absolutely everything with no contents insurance or anything like that is not really a great thought.