A little late reply, but my general rule to finish the game was to only use one small-curve-upwards directly before initiating a jump . Past that it was minimizing falling as much as possible because you lose way too much momentum if you're not on the track.
I also had trouble with Fun initiative as I had to remake my track 5 separate times as I kept making each catch-jump too low on the different hops over and over. It would have been nice if the game let you click a free-floating section of the track and gone "Move this up by one please".
Also remember to make the curve-turns BEFORE making the downward slopes to gain momentum. I flung my mouse out of the cart so many times. XD