I'm basing this off my Wipeout Pulse experience, not sure if this game is that similar:

Speed laps, race the first lap and speed through the finish so you have a good head start on the lap and then you still have another boost to use in the same lap. You only need 1 lap on gold.

A big problem I had was staying alive in the races that were 5 laps. The trick is to follow everyone fairly closely behind for the first three laps, get a good item, and then on the 4th kick it up all the way. You should have saved enough energy that you can get nailed a few times, and they aren't too hard to pass.

lol don't worry. You'll get better :P personally i can't pass second grid because the opponents are wiping the floor with me XD

hmm a good tip as someone said is using the boost from one round at the end so you get the boost with you in the next round. Its very important to hit the boost arrows and i if you're beginner use the ship mirage. Its very easy to use.

Remembet to pull tricks when you jump and always consentrate at not crashing.

Hit all speed pads, and use the air brakes

To be honest, learn the tracks. Learning the tracks help you a lot. Go to the single player single race and learn the tracks on Venum. After a while I know the tracks enough to put it up to Phantom and win. If it's time trials, remember the speed pads and try and chain them, use the free boost just after or before speed pads to get an extra boost. Also use the left right left function in the air for another free speed boost.

Of course, Zone is where it becomes a problem for some tracks, I tend to overcompensate on it.