From Before I Play
- Scan everything! Particularly things that either show up as a red scan point. A good chunk of your power ups will come from a scan that tells you it is made of x
- If you plan on doing a 100% items run, write down the names of the rooms where you get each missile/energy upgrade. You won't get them all yourself, and backtracking and having to remember which you picked up (or worse, which you may have picked up but then died and never saved) is a giant pain in the ass. It also helps if you grab the FAQ from Gamefaqs that has a checklist.
- All Missile and Energy Tanks make a distinct whirring sound when you get close, which happens even through walls.
- At the beginning of the game (when you first land on Tallon IV), after you've gotten the missile upgrade, make sure you backtrack to the Chozo Temple before moving on. There, you can start the big end-game fetch quest way ahead of time. In fact, you can have 11 of the 12 artifacts before you get the final suit upgrade, and after you get that, you can backtrack like three rooms to get the last one. It's much, much easier than getting there at the end of the game and finding out "Oh wait, time to backtrack across the entire world!"