Scan every room for a possible power-up. Often times you will need to solve a puzzle to reach a specific power-up.
Energy Tank
For every Energy Tank you track down, your maximum energy reserve will incrase by 100 points.
Space Jump Boots
These will enable you to jump a second time while airborne. (Press to jump, and press it again while in mid-air.)
Grapple Beam
This lets Samus latch onto specific energy nodes. The icon above a node will brighten when it is in range. Press and hold to latch onto one. You can shoot while grappling.
Gravity Boost
Once you find this upgrade, you will no longer be hindered by liquid environments, you will be able to float on command while underwater. Press and hold after performing a Space Jump to rise through the liquids.
Screw Attack
After executing a Space Jump, press repeatedly and with good timing to initiate and perform multiple Screw Attacks. As you guide Samus with , you'll damage enemies and cross huge horizontal distances. If you perform this while facing and touching certain walls, you will perform a wall jump.