You might remember the meaning of the character 同 with this easy mnemonic:
A husband mouthed (口) some curses when his wife asked him to empty a box (冂) of old clothes and find their old matching wedding shirts with "We are one (一)" written across them. She wanted to wear the same clothes which they wore at their wedding 20 years ago.
Using mnemonics to remember the meaning of Chinese characters like has a huge impact on how long to learn Mandarin it takes.