Playing Mass Effect 1 again this past week. One of the useful things to know is "what should I keep"?
Tier 4+ unlocks around level 18, tier 7+ unlocks around level 36.
Ammo upgrades: Around level 36 you should start keeping as many of the Tungsten VII and Shredder VII ammo upgrades as you can find. They stop dropping after that point, but are still the best anti-synthetic and anti-organic rounds.
Armor: Predator (green camo) 7+, Colossus (red/black) 7+, Phantom (turian only) 7+. Note that there are also the Geth Armory armors in the tier 7-10 range, but I don't care for their look.
Biotic amps: Savant is pretty much the only game in town starting at tier 7. Polaris at tier 4+ is okay.
Omni-Tools: Savant is best for 7+, Nexus or Logic Arrest Tool for tiers 4+
Pistols: HWMP Master VII or X, Karpov, Razer, Brawler, Raikou (tier 4+)
Sniper: Punisher 7+, Harpoon 7+, Volkov 7+, HMWSR Master VII or X
Assault Rifle: Geth Pulse 7+, HMWA Master VII or X, Raptor 4+, Tsunami 4+
Shotgun: Katana 4+, Avalanche 7+, Tornado 1+, Sokolov 7+, HMWSG Master VII or X