One tip: Email is a great way to gauge interest and generate leads. Use it to showcase your products and services to a relevant audience. Even if you don't have new products or services to promote, you may consider sharing new or interesting applications for your existing products. Make sure that you are including calls-to-action.
When advertisers come in to purchase any type of advertising they are excited and motivated, as they should be -- and it is these feelings that can make them delusional about a realistic ROI. It is our job as publishers, networks, and affiliates to explain rationally what the ROI will actually (should) be. If we are not upfront and honest about these things, we will be setting ourselves up for failure, because we are allowing advertisers to retain their delusional thoughts.