You might remember the meaning of the character 鼓 with this easy mnemonic:
You'll see a convex shape in the earth (土), and you should put your mouth (口) in it. Scholars (士) believe that doing that while holding an olive branch (支) in your hand will drum (鼓) up good luck for your business.
Using mnemonics to remember the meaning of Chinese characters like has a huge impact on how long to learn Mandarin it takes.