1) Anticipate your next move and start the Trak-Ball rolling in that direction ahead of time.
2) Complete each raceway as fast as possible because extra seconds mean extra points, and the extra time from one raceway is carried over to the next raceway
3) Try to maneuver around the Black Steelie, or try to bump him off a cliff to get rid of him permanently.
4) Move quickly to avoid being swallowed by the green Marble Munchers.
5) Watch for patterns, and time your movements right to pass by difficult obstacles.
6) Some raceways have alternate paths, so explore a bit and you may find an easier way to reach the goal. Bonus points are given for paths which are more difficult.
Cancel The Timer : Begin a game and then hold down either the 1 or 2 player Start and press the 'service switch' twice. The first press will glitch the screen display slightly - the second will remove it and give you 99 seconds to complete the level. This method adds 60 seconds to the clock, after which the normal countdown will begin. The clock will not appear to be counting down during the first 60 seconds, probably because the 99-second display was overflowed by the extra 60 seconds added. This method can be used multiple times per level for virtually infinite play time.
When you play 2 players, the winner of each level gets a bonus 5 seconds (I was better than my brother, so I'd always get the 5 seconds :D). If your opponent can make it as far as the silly race, that's an extra 25 seconds for the ultimate race, not to mention a possible extra 10 seconds with a wand. The opponent can also continue once (with the same time as the other player).
This isn't really a trick, but some people don't realize it : On the practice race, don't move when you start, and after a few seconds, a ramp will appear that will slide away the ball.