If your skin is dull you could try an acid exfoliant, but you would have to tread carefully as it could be irritating to your skin if overused. So a glycolic acid used once or twice a week. It will help to exfoliate off the layers of dead skin cells on your skin, which can cause dullness.
In terms of moisture, you could find a serum or moisturiser with hyaluronic acid, which is good for hydrating and plumping the skin.
I also find that a good Vitamin C serum (I use Geek and Gorgeous C-Glow) in the morning gives my face a nice glow, but again it can be quite irritating at first so tread carefully.
Also, niacinamide is suppose to help pores appear smaller, you can't get rid of them but some things help to make them look better.
If you do try these though you should use a sunscreen daily to protect your skin from sun damage, as they can make your skin more sensitive.
There is also things like retinol, but again that can be very irritating at first and your skin may look worse before it looks better, so you may not want to try that yet.
Ultimately with skincare it's usually a bit of trial and error. If you have the time and inclination you could try a few different products and develop a basic skincare routine. But maybe try out one ingredient at a time for a few weeks until your skin acclimatises.
Here is a link to the Geek and Gorgeous website if you want to build a basic routine - geekandgorgeous.com/collections/101-serums
I know it's a lot of products, but you would only need a few and they are very reasonably priced.
In terms of supplements, I take a multivitamin, iron tablet, omega 3 and vitamin d. Not sure if they are helping but I take them anyway.