Research.

Bands:
-Metallica
-Black Sabbath
-Judas Priest
-Guns N' Roses
-Led Zeppelin
-Iron Maiden
-Slipknot
-Korn

Once you get comfortable with the music attending concerts is very important to the subculture. Most concerts have mosh pits and headbanging is popular.

Clothing:
Thrifting is probably good