Well, congratulations! Once you've gotten to capable, your character is now respected in the Weyr as a dragonhealer. What you want to roleplay around that is now up to you - and to the people you can convince to roleplay it with you! You can largely ignore your rank, you can organize major plots, you can just be around to assist with other people's plots... it's up to you!
You can ground people and give 'weighty' advice. Just remember though that you still have to follow the principles of consensual roleplay you learned earlier and were tested on in the RP exam! Otherwise riders will probably freak at you when you ground them three hours before their weyrmate's dragon is scheduled to rise... and disobey you... and there'll be a big mess!
If you want to eventually move up to senior, or to help the senior, you should discuss your willingness to help with administratrivia with them! You should also be creating opportunities for others to roleplay... grab that 'training' dragonhealer and give them a lecture on what you're doing to that poor little firelizard that scraped all his hide off his belly! Volunteer to teach a class on your speciality! These things are not only deeply appreciated, they mark you as someone who wants to do things. AND - they're fun!
Welcome to Dragonhealing at Igen Weyr
Dragonhealing at Igen Weyr: The FAQRoleplaying as a Capable Dragonhealer
Basic Information: Anatomical notes