The most important thing is to not let anyone in.
Close it off, put a lock around it and make sure only you have the key, no duplicates and you don't let anyone else hold that key. Not ever. Make sure there aren't any little cracks that'll let people see, no peep holes, nothing that'll give them a clue about what's inside. Others, they have keys too, some easier to get than most. Take as many keys as you want, lose as many. But don't let anyone take your key. Yours should only be yours. No one else's. Some locks, they just need a kick and then you're in. Break down as many locks as you want. But don't let anyone break down yours. Yours should be sturdy. Strong. Surely unbreakable.
Do all that, and you'll be safe.
Rule number one: Heart.