I know this is old, but firstly: don't start with buying traffic from Plugrush. Their traffic is absolutely horrible. You need to have a really decent whitelist or enough money to spend to get a good blacklist going. But either way, Plugrush is not an easy place to start for media buyers due to all the fake/low quality traffic they have.
Also, as mentionned, revshare can take time. Some users will browse for up to a year before they trust the site enough to start spending. If you're lucky, you might land a whale who will spend $10,000 a month or more.
Cams take persistence and patience to build up a decent enough audience through revshare. Keep at it though! It will pay in the long run.