let go of the gas/hand break on sharp turns (if you master it you can drift through tight ring turns), don't boost in the air, line up your landings and jumps to stay on track, you just have to clip/go over rings, not through them, certain segments require you to let go of the boost to maneuver (for instance in Marin there is a segment where you have to drop under a tentacle and boosting anywhere near the thing sends you straight into it costing you valuable seconds/hanging you up and costing you the race), and of course, max runners.

Also only race during off hours if you are getting seconds added to your time.