Surveys are made for a variety of people, not one specific person. Because of this, you should make sure that the questions won't be too taxing on the participants brain. If the answer portion of the survey is too involved then you have a good chance of losing a customer.
A good way to guarantee this doesn't happen is to cut down on the open ended questions. These are questions that ask the person to give their opinion by writing their own thoughts. While open-ended questions provide great insight to the individual's perspective of the survey question, too many of these types of questions can be cumbersome for the survey taker.
Ask questions that can offer extra information to the survey like … “Are there any other comments you'd like to add?” The answers you get could be a big help in the report part of your research study.