Party Finder for <50 dungeons does not usually fill up fast at all - unless it's specifically for EXP (eg Dzemael Darkhold first room spam)

Duty Finder is sufficient. Just say you've never done them before and you'll likely get a quick explanation of them. Even though places like Qarn are fairly challenging to new players, to you - who's already been to 50 - they shouldn't be a problem.