Your IRB has some critical issues for you to consider: two of the main ethical concerns are protection of at risk populations and anonymity. The at risk populations may not be what you think. For example, prisoners are considered part of this group as is one obvious group, the mentally ill.
Consider whether you are going to include protected groups in your study, If you are, how will you ensure that they are not harmed by your research? If not, how might you ensure that such a group was protected if they had been included in your study? How will you ensure that those who want to remain anonymous are not identified?
In your IRB, you will be asked to ensure that your participants can withdraw from the study at any time without penalty. How will you ensure that this happens?
OR Answer this:
Here is an example of what not to do: what's wrong with this picture (there's more than one thing wrong)?
"In order to withdraw from the study, participants will call the researcher and come into the office to fill out a form. Their information will be kept and used for the part of the study they completed by that time. It will not be used for future research."