I have just started using Neroli Firming Intense Facial Serum by a brand called Super Facialist By Una Brennan. It is amazing!! After 2 days have noticed a huge difference to the overall look of my skin, fine lines around my eyes are reduced and it actually feels, well, firming! And it's not crazy expensive, about 15 quid I think, bought it in Boots.
I've tried all sorts of serums from around the 50 pounds mark downwards and this is the first one where I can honestly see a marked difference.
Highly recommend a try. It smells gorgeous too.