• Avoid hitting the 5 "eggs" at the bottom of the canyon -- you can't kill them, but they can kill you
• The robot is useful for more than just rescuing PANG clones -- use it to move skulls down to the bottom of the ravine, etc.
• Try not to open the caves until phase II
• Save your smart bombs for phase II, and don't necessarily use them for blowing things up. You can use them as a temporary platform to drop rocks onto.
• For lots of points in phase II, build a "maintenance free" escape route -- that is, set it up so you don't have to drop any more rescue supplies after you open the caves.