What's the Best Procedure for Wrinkled Aging Arms?

Thank you for your question regarding wrinkly forearm and upper arm skin. It is difficult to answer accurately your question without pictures, but I will try my best.
It sounds like you have extra forearms and upper arms skin with minimal fat. This is common with normal aging. Unfortunately, as we age, we all lose skin elasticity. If you had just excess arm and forearm fat and had good skin elasticity, I would suggest forearm and arm liposuction. Unfortunately, due to your loss of skin elasticity, absence of forearm and upper fat, and presence of excess arm skin, I would suggest skin excision.
Due to the presence of forearm and upper arm skin, I would suggest a combined procedure addressing both the arms and forearms. The procedure would remove skin from the upper arm and the forearm. Depending on physical examination, the incision would extend from the armpit to the mid-forearm or the wrist.
Good luck with your quest for skinnier forearms and arms.
If you have any questions, please do not hesitate to contact my office.
Sincerely, Dr. Katzen

Your best option is to tighten the skin with some type of arm lift.  Definitely consult with an expert in the field to understand your best options.  The good news is that scars tend to look great in older patients.

How to Treat Aging Arms
There are several different options that may help  but all to a degree. An exam would be necessary. Prescription strength skin lighteners and or certain lasers will help with the sunspots as well as using sunscreen daily. Their are procedures like RF, radio frequency that may help but only a  small amount in my experience. See a dermatologist or plastic surgeon for further advice.