When owning and and maintaining a website, feedback is vital to allow you to improve it. Once the site has been up and running a few weeks or a month, then it is a good time to start to ask visitors what they think of your site. This can be done in a number of ways. Many companies opt for a quick pop up that prompts people to complete an online survey. This is not always popular as not many people will take part in a survey if they have little time or are at work. They may be more inclined to do so if you are offering to enter them in to a prize draw for example.
You could call customers up and ask them about their experience as if you have them on the phone they are more likely to participate that by sending them a letter or email.
When creating a survey keep it short and to the point to increase the amount of people that complete it.