You might remember the meaning of the character 慎 with this easy mnemonic:
I'm not a very cautious person, I've burnt myself with lanterns (忄) before, and have ten (十) scars around my eye (目). I also have one (一) scar here from running into the table (几).
Using mnemonics to remember the meaning of Chinese characters like has a huge impact on how long to learn Mandarin it takes.