The nature of your profession does not really matter but whatever field you are in, you must have heard the phase that clients are always right. Now, this does not mean literally because they cannot be right always but at times, you have to accept whatever they are saying and do things according to their desires. If you want to have a successful business, you need to have a satisfied client and this can happen only if you treat your client in a right way.
Poor graphic designers have to face such situations quite often. Obviously, a common man won’t know graphic designing more than a designer but designers have to accommodate requests of clients into the designing which does not improve the designs in most cases. Clients also need to understand that the designers are called professional for a reason. Obviously, they have studies the minute details related to designing and they know better than you. But then again, getting rigid clients is a routine and designers, at the end of the day, have to accommodate their requests in one way or the other.To reinforce the notion that clients are always right, you could do a sticker printing campaign and stick them around the office to remind yourself.
Now, since we have convinced you that clients are supposed to be right, this does not mean that you have no right to give your ideas and suggestions to the clients. See, clients are paying you for work and it is your moral, ethical and professional responsibility to guide them properly. If they are making a stupid request, do tell them that this is going to destroy their project and try convincing them on why you think some other thing is more perfect for their project. If you really want to avoid useless arguments between you and your client, you should focus more on understanding the product and project