i was like this for a while too, it's a lot easier to boost once you have an xinput controller. but the main trick is to spam the trigger button until you dash and then hold it down once you start dashing. you'll stay dashing for 2 seconds then youll have to do some tricks to gain more speed.
and as for the meter colors, the blue is your speed level. the pink is the trick level. lets say that you have 2/3 of the meter filled with pink. you can do a level 2 trick in the air if you hold down left trigger while you trick. be sure to complete the trick before you hit the ground otherwise you will lose all your speed. Zinnie is actually a lot easier to gain speed with once you unlock her.