What to charge for ads

1

im hopefull am going to be getting more traffic to my website soon, and iv setup a place to show ads, im not going to use google, or anyone for the ads. the only thing im not sure of is what to charge. its going to be ecpm based, and the ad is 150x100 pixils. there will be 4 spots available, and they can be combined into bigger spaces. i was thinking of 10-20 cents but now im thinking that may be too low. im totaly new to advertising and would like some advice.