I have a website with really good traffic and have a couple of companies wanting to buy advertising space how much should I ask for? Our website is well established but I have never sold advertising space and would like to start doing so.

It's hard to give an ad rate because it depends on a number of factors

1. the audience the site attracts – a site for high net worth individuals, even if traffic is only 10,000 pageviews a month, can command higher rates compared to a site that attracts teenagers and gets 10 million pageviews a month

2. traffic levels – the more traffic you have, the higher rates you can charge compared to other sites in your segment

3. the sizes – normally, the bigger the size, the higher the rate. Hence, a wide sky can charge higher than the regular sky. Or a large rectangle can have a higher price than a button. Or a leaderboard can have a higher price than regular 468×60 banner. Rich media ads are higher than static ads.

4. advertiser exposure – will the advertiser buy all your ad inventory in various formats, or will they buy for longer periods of time

To find out the rates, here are some strategies:

– go to your competitors and check if they have online media kits and check their ad formats and their rates. If not published online, send them a request (try to pretend you're interested in advertising with them)
– check out the rates you're getting in the banner ad networks such as BurstMedia.

One thing you will need to provide: a way for advertisers to see the results of their campaign in terms of impressions and clicks. So you need to have an ad server. Check out OPENX http://www.openx.org/ which is a free ad server that allows your advertisers to check their stats in real time