How do i become a player moderator in Runescape?

Just be helpful. Report the wrong-doings you see. Don't go hunting for people to report though... You might get someone who really wasn't doing anything. Be nice on forums if your a member. Mainly just be a overall positive influence on the community. I keep to myself. I'll help if someone asked but yeah. Personally think being a player mod is over rated. Too many questions when people see the crown. lol