Pictures would help. There are lots of people here with much experience restoring these trailers, but they've got to see what you're doing.
By way of general advice, first take care of any leaks. That should keep things from getting worse. Floor rot is a big enemy.
Sounds like tires and running gear can come later, assuming that you don't have far to move it from your neighbor's place to yours. If you do have to move it some distance, replace tires, check and service wheel bearings, check brakes and get them working.
And, above all, welcome to the forums.