If you can avoid using bombs on arcade you'll get a higher scoreRemember to zoom through stuff as well, and make sure to use the right weapon for the job (enemies are colour coded according to what weapon will be most effective against them). Practise on planet mode as well
And try and relax - some of my best scores come from when I'm quite chilled, if you panic you're probably more liable to crash into stuff
Have fun!!!
edit: and make sure to pick up the right power ups - mainly rock crushers for the first planet then start to top up your gold melter, after that you can work on you ice-crusher. There's a few tips posted about in this thread too
further edit: shields are your friends. Picking up a further shield when you already have one sets off a handy bomb, so they're sometimes worth rushing in for (be careful though). Another tip, you don't have to destroy all enemies - the mines will blow up anyway over time so you can concentrate on other things.
What do you mean by zoom through stuff? Oh and when you say colour coded do you mean a red baddie = flame to kill?