The subcutaneous connective tissue and thyroid gland are separated with microsurgical dissection scissors all along the line of the skin incision. The skin is mobilized, and retractors are placed for better access. The neck muscles on the side you want to work on are carefully separated until the trachea is visible. The retractors are adjusted to include the dissected neck muscles. Be careful not to harm or occlude the trachea. Isolate the external carotid artery all along its exposed length.
If you want to work on the external jugular vein, continue the dissection in a lateral direction onto the Sternocleidomastoid muscle using the same setup.