Paid Advertisements

Hey you good people,

Hope your nearly ready for Christmas.

I am wanting to do some paid banner advertising for an adult site i have. I have worked on optimizing the landing page of my site. What things should i look for when buying paid advertisements, like alexa rank, how many people use the site etc. Should i keep my budget low initially and how can i track results?

Thank you very much for any advice you can give. Take care.

Jimmy