According to my text book on Cosmetology (Milady's Standard Cosmetology page 624)(I am summarizing important information not writing exactly everything)
The best way to support skin is to eat a proper diet (to help regulate hydration, oil production, and overall function of cells). Eat foods found in all three basic food groups. Fats, carbohydrates, and protiens.
Vitamins aid in healing, softening, and fighting diseases. Vitamins A, C, D, and E have been shown to have positive effects on the skin's health. Internal is better than external, though external helps some. These are the main ingredients in most skin helping supplements, lotions, and revitalizers.
Vitamin A -overall health of skin (health, function, and repair, antioxidant) , improves elasticity and thickness. In topical acid form it is main ingredient to Retin-A.
Vitamin C- absorbic acid, repair, aids and speeds up healing, fights aging, promotes collagen (helps skin be healthy and firm)
Vitamin D- healthy rapid healing skin, best source sunlight (limited), also helps bones (added to milk because of this)
Vitamin E- tocopherol, with vitamin A helps fight UV rays, great internally or externally, helps heal damaged skin (even burns)
Water- Drink Pure Water- take body weight divide by 2, then divide result by 8. example 160 pounds/2=80/8=10 glasses of 8 ounce water; add 2 more if you do intense physical activity.
So first, eat well to create building blocks, drink Pure Water sufficient amount, take a multivitamin (helps with all basic vitamins), add supplements for A, C, D, and E internally
add lotions, conditioners, and nail oils/nutritions to troubled areas externally(find one best for you),
Nails- B vitamins, gelatin, and keeping them hydrated (oils, moisturizers, and sealer/protectors)
Besides trying to buy something to apply on to your skin, try internal solutions (which may be more effective). External lotions and skin care depends on your oil level (oily, dry, med), and need for other protections such as UV (out in sun all day, or skin problems (rashes, skin allergy, skin medical condition).