The first category: English words (use English to arm yourself and look high-end and classy, ??but you must find out the meaning of the word, otherwise it will be embarrassing).
Representative figures: meiko, rookie, uzi.
The second category: abbreviations (no skills required, just like it, capital letters are recommended).
Representative figures: Wxz, Mlxg.
The third category: pure numbers (just a code name, so casual).
Representative figures: 957, 369.
The fourth category: Pinyin phrases
Representative figure: Xiaohu (小虎).
Category 5: Real name (if you think your name is the nicest, you can consider it).
Category Six: Ancient Poetry Types
Representative figure: Ye Xiu (ID name: Jun Moxiao).