i have been a player mod for about a year now.
before getting invited, i was so envious of those people who got chosen. i really wanted to be one too. but i knew my chances were slim, because there are a lot of players out there that would make good player mods as well.
so i continued playing as i normally would have. i trained my skills, reported only the serious offenses, and was helpful and friendly to anyone who crossed my path. i also occasionally posted on the forums helping out people with their quest troubles, and clue scrolls. i know one of those things listed is what got me noticed. but i am not sure what it is. they don't even tell the player moderators how they choose us!
so my advice to you is -- be yourself. you seem like a very nice person, with a good head on your shoulders.
-report only when you see fit. when you do report, never be rude, or talk about how you just reported them. jagex tries to find users who are able to report the right things, and have a good attitude about it.
-be kind to your fellow players. personally, i honestly think this is the main reason i was chosen. i use smilies way too much, i always use good manners, ie; please, thank you, no thank you, you're welcome, good luck. and i have never, not even once, called someone a noob. jagex chooses people who will represent the game in a positive way. kindness is a good way to charm them lol.
-secure account. you obviously have that down for sure lol. which is awesome. jagex wants a potential player moderator to have a good sense of account security. this is very important to them.
the only thing i would suggest is to keep your reporting to a minimum. it's 100% great that you report, and you ARE reporting all the right things. but sending in for example, 3 serious rule breakers will get you more noticed than sending in 25 general rule breakers. i had only reported around 5-10 people before being modded.
best of luck to you! hope to see you joining the team soon ;)