Race The Sun

This shouldn't be super difficult after you've played a few games, but the best way to do this is to go through a world portal (green rhombus shaped things unlocked at level seven) and collect as many tris as you can. I find it trivial to get at least +10 or 11 multiplier, making your score rise rapidly. From then on, try not to hit anything and you should get it by around region 4. I also advise that you find a good path on that days level and stick to it, perfecting it through the first region or two, to maximise tris earnings.