It could be a juvenile so you wont be able to know. Do you know where it's native or where it was seen?
black snake
the Australian brown snake even tho it ain't brown prob a relative, also known as easten brown.
there are two, dun which is a beige colour with a black mane and tail and palomino which is slightly paler with a white mane and tail.
mud snake
The red-bellied black snake, which is native to eastern Australia, is black with a distinctive pink-red belly.
brown or black leggings with a cream beige or white top and a black, white, or brown jacket! And maybe if you really wanna get fancy wear some kind of brown, black, or white jewelry or headbands. :)
Garter snake
I believe you are refering to a black rat snake.
Northern Black Racer
Eastern smooth green snake
I believe you are referring to the Grey Rat Snake.
That is the endangered Georgia Tube snake.