Other common symptoms. Besides tremor, the most common symptoms include: 1  Stiff muscles (rigidity) and aching muscles. 2  One of the most common early signs of Parkinson's is a reduced arm swing on one side when you walk.3  This is caused by rigid muscles. 4  Rigidity can also affect the muscles of the legs, face, neck, or other parts of the body.he most common cause of non-Parkinson's tremor is essential tremor. It's a treatable condition that is often wrongly diagnosed as Parkinson's. Besides tremor, the most common symptoms include: 1  Stiff muscles (rigidity) and aching muscles.