Do research into the subculture. I provided a good base, but there's a lot more. Especially the music, history, and just the punk scene in general, there's so much to it and i barely put any because it would have taken too long.

Research into the political beliefs!!! Read books about it (make sure they're by authors who have that political belief). Political commentary books are good too (the highrise, animal farm, 1984 etc.)

Listen to the music.
Here are some bands to get you started:

Riot Grrrl
- Bikini Kill
- Bratmobile
- L7
- 7 year bitch
- slutever
- le tigre
- destory boys
- the regrettes

not riot grrrl
- sugarcubes
- the ramones
- green day
- sex pistols
- misfits

tip: i have a note in my notes app where i have a list of all the bands i want to listen to and when i listen to them i click the bubble thing. if i like the band i write it in a list i have below the bands i need to listen to

fyi! you do not need to always listen to punk music, you can listen to any kinds too. just make sure you enjoy punk music and are well versed in it:

clothing: Thrifting!! It's cheaper than getting it online, and you usually modify the clothing you thrift. this comes from 1. the anti-consumerist views, and 2. most punks aren't rich (the movement stemmed from the working class) and thrifting is affordable. and since punk is mostly diy it's hard to find punk clothing online unless it's accessories. Repurposing your old clothes.
Examples:
-cutting sleeves off
-painting things on to shirts
-ripping shirts and putting safety pins
-making patch jackets/pants
-dying/bleaching clothes