The first cause of blade "run off" is wheels that are not coplanar. This is easy enough to check, fairly easy to remedy and the VERY FIRST thing that must be accomplished. Without making this happen, all other adjustments are meaningless.
Much has been written about bandsaws. Perhaps the best book ever written on the subject is Lonnie Bird's "The Bandsaw Book". Bird arranges the things that MUST be done to make a bandsaw cut, AND the order that they must be achieved. Making any other bandsaw adjustments before making the wheels run exactly parallel is useless and downright dangerous.
Bird's simple to read and understand "cookbook" gives step by step instructions in properly setting up and checking a bandsaw. IMHO, this book should be a required "safety manual" for anyone who uses a bandsaw.
This book can usually be purchased in Amazon for +\- $10.