yeh agree with all that start nice and slow untill both you as a driver and the rider are feeling comftable
one main thing i will add however and this is more to do with tubeing than most other towing and that is to watch the turns and leave yourself PLENTY of room to allow the tube to whip out
i have seen people getting whiped into trees and although thankfuly i have never seen it there are DEATHS each year from exacly this with people not giving themself another room for the whip and putting their loved ones into moored boats, pontoons, trees, riverbanks,and other such obsticals
the tube when you turn will whip out from the wake and momentum will force the tube out wider than you are turning