Basic prompt

score_9, score_8_up, source_anime,
1boy, aang, bald, white-arrow forehead tattoo, tattoo, 
yellow pants, orange capelet, orange belt

Avatar State

avatar state, glowing eyes, glowing tattoo, 

The original series style

To get something close to the original style of the series, I suggest using the following text:

1990s (style), film grain, anime screencap, flat color

Please, comment on your own methods for this task!