You have worked hard on your website for a while, and now, you suppose that it's time to monetize your site by selling advertising banners, videos, etc. How to seduce advertisers ? You should make them interested in your website, confident and... loyal once they give you a try.
It's whole a process, but it's not a machine. The closer you are to your potential advertisers, the more likely they will trust you in return. Simply keep on mind that your potential customers (advertisers themselves or ad-agencies) really appreciate to be listened and feel your interest on what they do and what try to buy. It's human !
Perhaps, you are impatient to earn money from advertisers, so they are, reciprocally ! And they never donate ! That's to say, you should pay increasing attention to the expectations of your future advertisers : what do they want to communicate? how can you help them to measure their campaigns ROI (Return On Investment) ? etc.
Then, remember that you are not the only publisher trying to approach advertiser. Usually, this last is continuously flooded (may be bored) with offers from new and popular websites. Sometimes, advertiser just prefers to invest in mailing or offline campaigns.
The question is, how unique is your specific site ? Why advertising there instead of the competition ?
One first step consists on preparing a media kit for your website. Stay tuned for next tips !