Thanks for the query.
Skin care needs to be customized based on the presenting complaints.
Based on your description, it appears that you have acanthosis nigricans. These conditions have a strong relation to one's internal health and it needs to be evaluated as often quoted - Skin is the mirror of internal health. Attempting treatment without understanding the pathology will be futile and make the course longer.
Your dermatologist will decide a treatment plan for you after a consultation.
Apart from active pharmaceutical medicines, a healthy diet and lifestyle is mandatory to achieve results.