There are lots of "right" answers ... so you have to pick a strategy that makes the most sense to you and your lifestyle ...
Thoughts for you to consider:
1. Do you have the time to manage customer service and customer relations on a monthly/weekly/daily basis. Trust me, "by the month" means daily work for you ...
2. Who do you want to sell to? Do you want to sell to people who are looking for traffic (typically traffic that converts) or are you looking to sell text-links to people who are looking at links from a
SEO perspective?
3. If you are looking at selling based on traffic. Do you know what your traffic is and what your demographics are. A lot of buyers are looking for traffic that will convert - do you think that your demographics are the type and quality of traffic that will convert. If so, you can test your website out yourself by focusing on some affiliate programs to give yourself a feel for how much your traffic might be worth ... I know of one PR2 website that makes me a fortune because its traffic converts incredibly well ...
4. If you are looking at selling links to people who are only looking for
SEO links, then you need to evaluate how much those links are worth ... and for what duration ...
4A. There are a lot of people that only want to buy a text link for a very short period of time just to get their site crawled by the search engines that much faster ... a PR6 text link is a great way of getting a site crawled almost instantly ...
4B. In most cases, you will earn more by selling a link for a longer period of time than you will for a shorter period of time because the "renewal" rate drops off very quickly. There is also a greater "cost" in terms of your time to service and support renewals and new customers ...
4C. There are a lot of webmasters who do not want to sell links or advertising for longer than a month or two because they think that their page rank might go up and thus they might "loose" money on links that are sold for longer periods of time. While it is a valid perception, a longer term customer usually will make you more money ...
5. And another option is to use a third party provider. Google adsense allows you an option of image only ads to fill banner space and the neat thing about these ads is that their 300x250 ads do not seem to get blocked as much as the traditional banner ads do ... there are also a wide variety of other third party text, link, and banner(image) ad services out there like Adbrite. Different services tend to have better results depending upon the theme and style of your website ... just because one may not perform incredibly well does not mean that another might not perform better ...
There are lots of other "right" ideas ... consider them all and choose what makes sense to you and matches your lifestyle ...
Greg