When choosing a serum you first need to decide what type of skin you have (normal , oily or dry ) and what it is you want to achieve by using it. To prevent ageing you would use something with antioxidants. To reverse ageing it would be one that had Vitamin A or hyaluronic acid to nourish the skin.
I use serums under my moisturiser and a few of my favourites are ASAP Super C serum, Dermaquest C3 serum & Skinceuticals Serum 20 AOX. These ones stimulate collagen production, contain antioxidants to fight free radicals and help brighten the skin... 3 in 1 .The other favourites are the Dermaquest B5 serum & Skinceuticals Hydrating B5 Gel which contain sodium hyaluronate for hydrating the skin. I feel between the Vitamin B & the Vitamin C I should have everything covered to give my skin maximum nutrients. Dermaquest have also just released a new B3 product called Niacinamide Youth Serum which is meant to improve uneven skin tone and fine lines. ( It's funny how anything with the words youth and skin in it makes you want to immediately give it a go ). I tried a sample of this but I think it was too rich for my skin as I have broken out in spots and the difference in my skin isn't noticeable enough to persist, so would stick with the B5 serum . As my skin tends to get oily, I think it is better applied to dry skin.
So if you're looking to do abit more for your skin to keep it in great condition - why not try a serum or two .... your skin will definitely thank you for it. xx