Be a light leak nazi. Make sure the filter holder is always in place, tape up the door, make sure that you're covering up the viewfinder completely with your eye and if you can't, switch the viewfinder shut (not sure if all bolexes have that option). Light leaks are awesome the first couple of rolls, then you realize it's incredibly distracting. Also, this applies for any film camera, always reshoot the last shot you did before the roll ran out. One last thing, always remember to plan around the 30 second time limit. You're not shooting the next russian ark on your bolex.