In honor of War for Cybertron, I decided to trudge through the game a few months ago. Like you, I never actually beat the game when I was younger, well, without cheating. However, this time I persevered, and it's not really that hard of a game. It's more bland than anything, and has some poor level design. I have a few tips, but please note, these are for the Maxmimal side, I never beat the Pred side. However, some of these tips may apply:
1. Magic jumps. If there's a spot or platform that looks like you can jump to, you probably can, but it feels awkward. So just get a running start, and hope for the best. I know there's a spot in the Polluted Zone I had problems with because there was a gap that was an unobvious jumping spot. The Volcanic Zone has some really, really bad platform jumping areas.
2. Speaking of the Volcaninc Zone, there are some firey barriers. A couple you have to find a switch to deactivate, but there are others you have to jump through. There's little distinction in the graphics between these barriers, and got me stuck.
3. Another Volcanic Zone tip, the first level boss can kill you with ONE HIT!! Oh, but it gets better, as he can kill you before you ever see the blasted guy. Very frustrating boss, all I can say is strafe, strafe, strafe.
That's all I can remember off hand. If you need anymore help, just post and I'll try to remember how to get through that area.