My first step would be to remove unwanted advertisements that may drive away business, particularly on the mobile platform. So if for example there was a massive f*** off "ADVERTISE YOUR JOBS!" sign sticking across the page, I'd probably trim that out of the picture.
Secondly, I'd probably try to move away from being purely a forum (hypothetically with some other junk littered around the top that nobody looks at). I'd give people profiles with a professional edge (think linkedin not facebook), yet also protect anonymity so people are free to post without names being revealed to the casual observer. Ergo a "friend" or "connection" esque system would need to be put in place to allow you to link up with other like minded top people in whatever particular niche market we might be talking about.
So for example if were were talking about facial fashion as our niche, this way if a potential client Googles "how do I make my eyebrows bushy?" they would find a nice thread of peoples views on the subject and could pay to connect with any they feel may be worth employing. Also visa versa - client posts an issue and we all have a pop at pitching the best way to crack it (for a little fee).
You could then start thinking about PMs between connections (ergo potential fee revenue), membership fees and most definitely a rating system.
Or of course you could just post some nude ladies.