Yes, imposing a return policy can sometimes hold you back for fear of losing potential buyers. But businesses need to declare one, since time is gold and there are products that need to have this policy (and a non-return policy for certain items) stated in detail.
You can impose conditions on accepting returned merchandise, and you can also state that you need to avoid those with return reason as due to whim, that the buyer changed his/her mind. You can start your paragraph with an intention to provide the best customer service, and hence the need to state the return conditions clearly.
I find this one paragraph quite fine, I copy paste from Link hidden: Login to view
Customer satisfaction is our top priority. Every transaction should result in a pleasant, convenient, and successful shopping experience. If you are dissatisfied, we are happy to offer a full refund or exchange on the return of any merchandise within 10 days of the shipment date excluding any shipping, insurance, or auction charges where applicable. To streamline your return, we ask that you please note the following:
Then below this you can enumerate your return conditions.
It will also help to tell buyers that if they are uncertain of the itemâ€™s quality or appearance, they can send you a message for clarification, before purchasing the product. :)