随

 

随时 any time 随地 any place 随便 like you please (lit. as convenient=memory hook here)

 

Phonetic clue:

Sui-dynasty 隋

随 This character is not a compound of simpler characters, instead it is a rearrangement, simplification and mutation/corruption of other characters. The idea is: follow, submit to (the sui dynasty). It doesn't appear to be part of any series, but a real weird character you must simply memorize as a stand-alone.

https://hanziyuan.net/#%E9%9A%8F