Many power-ups, especially Missile Tanks and Energy Tanks, are hidden in rooms that are not immediately obvious. Always look for suspicious blocks that can be destroyed by bombs or the Screw Attack. Some blocks require multiple bombs to break. Additionally, some walls are 'false walls' that Samus can simply walk through without needing to bomb them. These are often found in dead-end rooms or in areas that seem to have an unreachable item. Experiment with bombing every wall and floor in rooms where you suspect a secret might be. The map can also be a good indicator; if a room has an unexplored section, there's likely a secret passage.
