well, you need to assess your traffic first. to save yourself the frustration, avoid ppc strategies unless youre going thru google or yahoo. a flat monthly fee is a good way to do it but anybody that will advertise with you needs analytic reports first. if it is a newer site, and you lack the traffic via organic rankings, you will probably give the ad space away at first. i have a site i sell listings on, and i charge $1500/yr but the site gets about 500 visitors a day. you also need to present your media kit to any potential advertiser.