Insectoid is one of those games where I just have to try to achieve a high score, and so I thought I'd share some tricks I picked up in case anyone else finds them useful too.
Space is a dangerous place!! Sometimes you'll find that it is just too dangerous to go after a bonus coin or honeycomb. Don't feel bad, it's better to live than die trying.
Multipliers are the key to a great score! When I see a multiplier show up I like to charge my weapon and try to shoot it with one of the first shots of the charged weapon. Then I'll sweep across the playing field looking for a good cluster of enemies for my charged weapon to take out. This is also a good time to use your ship's powerup if you have the combs for it. Finally, you get more points for shooting down enemies that are attacking, so focus on those rather than the enemies waiting harmlessly in formation.
Bonus rounds are tough, but key. Spend some time getting to know the patterns of ships in bonus rounds, and try out a couple strategies. The ships will try to trick you with sudden direction changes, but once you learn the patterns you'll be on your way to 100% bonus round clears and new high score heights!
Accuracy within levels is a tricky thing. If you don't mind taking your time and waiting to shoot enemies when you have a direct shot, you can improve your accuracy, and thus your accuracy score. Stick with single shots, and keep moving around so you'll be in place to take your next shot. Make sure you stick with the same ship as you play because you'll need to have a good intuitive feel for the speed of your bullets to successfully maintain your accuracy. Can you achiee 100% accuracy rating in a level?
Have fun! Sometimes working towards a high score can be nerve wracking and can try your patience. Play a round without going for a high score - just try to blast through levels as quickly as possible or try out different ships. This can help loosen yourself up so you're ready for another go at a high score.