Servicing the movement is something that is normally done as part of preventative maintenance. Cleaning the dial and hands is an less common and risky maneuver that would only be considered as part of a serious restoration. Neither servicing nor restoration would be recommended in this case since you are planning to sell it. The condition of the watch doesn't justify it and it's not a high end watch in any case, so the upside isn't high. IMO, you would lose money by trying to restore it.
For example, maybe you can sell it for $300-$400 now. Or you could invest $400 into it, servicing the movement and cleaning the dial, with luck make a small improvement, and sell it for $500-$600. Or after that investment, the dial could look worse, and it becomes a parts watch.