Chirod

Mostly just guess, a little later in had wind,a hair earlier in tail, hopefully after your warmup passes you have a feel for it for the pass that matters. More important then all that though is keeping a tight line through the glide on your gate. Even if you have more or less speed then 'ideal' if the line is tight you'll be able to choose when you cut for the gates which is usually good enough.

Camero has some glove liners that work well. Basically just a little wetsuit for your hands. during the summer I usually tape my hands, during the winter I just use the liners underneath my usual gloves. Works good into the low 40s f

Easier passes all day long. Every successful change to my waterskiing in the past 5 years has been from working on things at my easiest pass, and _slowly_ working the changes up into harder passes. Running deliberate, smooth passes is hard at all line lengths and all speeds, and to often I see skiers ignore flaws at their opening passes just because they ran the pass and weren't feeling rushed. That said, you do have to keep the feel of your hard passes, plus they tend to make your flaws obvious, giving you something to work on.