Supplements that preserve your general health will also help maintain you on the outside more or less. Those are the supplements that upregulate your endogenous antioxidants (SOD, glutathione, catalase) will give you a glowing look and help skin resist damage. Pycnogenol is good (but expensive) one for that. But there are plenty of cheaper ways to get OPCs. OPCs will help to preserve skin by reducing glycation and preventing the breakdown of elastin. You then want something to increase collagen production and preserve elastin. Two examples here are hyaluronic acid (expensive and slightly elevated risk of cancer) and besides OPCS, green tea extract, EGCG. I have a hunch that olive leaf extract is even better than green tea extract, though it hasn't been studied as much. I really believe that everyone should be taking either green tea or olive leaf extract for general health.
Here are some skin-related supplements that I take:
l-lysine (collagen & general health)
beta-alanine (anti-glycation)
sodium ascorbate (anti-glycation & collagen production)
benfotiamine (glycation)
olive leaf extract (anti-glycation, preserve elastin)
fat soluble carotenoids (lutein, zeaxanthin, not too much)
hyaluronic acid and collagen for building up collagen
root and bark teas for OPCs
If I wasn't cheap I would add pycnogenol.
Exercise and nutrition are super important as Stefanovic has pointed out.
The above isn't so expensive. Where you'll really break the bank is topicals and injections, which IMO aren't worth it.
(Oh and remember that high cortisol will undermine everything else
)