Thank you sooo much! Especially for the suggestion and the help. Getting advices from pros like you is always helpful for a self-taught artist like me ^^

First level = Overall Shape (If you're talking about humans - it'd be the shape / pose of a person) and basic planes for light, etc...
Second level of detail = eyes, teeth, refine it....
Third Level of detail = Pores, freckles.

^This. A lot of time I stuck at this "big > small > smaller detail" part, which I think because I rarely use reference. Like this robot for example, I've seen countless robot designs already--from games, movies, etc--and I can picture their details like the bolts, inlays/onlays, greebles, some random number code, and stuff like that, but when I try to put them into my model, my mind goes blank, the progress slow down, I got bored and start another one lmao.