You might remember the meaning of the character 澳 with this easy mnemonic:
There's a deep bay in front of our house, and you can see droplets (氵) of rain disappearing into the water if you climb up to the roof (宀). If you throw rice (米) into the bay, you'll also see some big (大) fish come up to the surface.
Using mnemonics to remember the meaning of Chinese characters like has a huge impact on how long to learn Mandarin it takes.