A customer satisfaction survey shouldn't be too long. Ten questions are more than adequate. Keep the questions simple and apply a grading system that is easy for you to use. Some businesses simply use "Excellent" to "Poor" in the response boxes; others prefer a numbering system. It's up to you. The technicalities of market research mechanisms aren't the issue here; what's important is how your customers feel about your level of customer service. If you give out 50 forms and 40 come back all saying that your service stinks, you might just have a problem.
Print the form so that it looks professional, and make it easy for people to fill in and return to you. I would suggest that you only print a small number of surveys at first because there will almost always be changes to the questions asked, which can be a problem if you have 10,000 printed surveys sitting under the counter.
If you are out and about and you see other companies' customer satisfaction surveys, grab a copy and compare their questions to the ones that you ask. Look for ways to improve the questions that you ask. I have a box full of survey forms from around the world that I use whenever I am planning a survey for my clients. Simple wording changes can have a big impact on the number of survey responses and the accuracy of the information collected.
With the advent of the internet, customer satisfaction surveys can now be done online; and while the response rate is quite low, it does provide an extra source of customer feedback.
I always like to sit down with clients at the end of a project to have a debriefing. This is a face-to-face customer service survey, where we ask them to give us their perception of how the project went - both the good and the bad. This gives us the opportunity to address immediately any areas that the client isn't happy with, and it provides first-hand feedback on what the client liked about dealing with us. This is also an excellent relationship-building exercise. Our closing question is always "Can we do business together in the future?" and the response is always "Yes".