First you've to know the interest of your visitors. Put a poll to your website or blog to find out what make them happy. you can quickly put together a questionnaire that sheds further light on where your advertising focus should be. To get the best results from your poll, Make it short, and perhaps even give away a gift to make it worth the respondents’ time. People rarely fill out surveys without an incentive.
You can create a poll with these services:
PollDaddy
Survey Monkey
Micropoll
Vector Tuts+
You can create a poll with these services:
PollDaddy
Survey Monkey
Micropoll
Vector Tuts+
If you would rather not go this route, a simple request for feedback might work. Just put the word out that you are looking for input and then ask for comments.