...as the front tires roll down into depressions (think driving across a small ditch) the back of your box blade will raise up causing you to deposit unwanted material...
For me, using a box blade on a gravel driveway, this was the most annoying part. I can't say I've ever totally solved it either - as far as I can tell, it's just a basic limitation to a rear-mounted implement on a small tractor. (pushing the fill backwards at least on a few passes does help, though)
It is THE reason road graders have a long wheelbase.
As Scissors notes, go slow. It's definitely possible (actually likely) you and a box blade will make your gravel driveway worse, at least initially. You need to get proficient at 'feathering' your 3PH lift control. Sometimes slow forward speed and 'float' helps.
All this assumes OP is using the box blade on a gravel drive. If it's to be used for grading or backfill around new construction, for example, a different 'learning process' is at play.
All that said, the box blade has been a great value for me - I've pushed and pulled around countless tons of misplaced material, with generally good results.