Hi OP, the reason I mentioned the Ordinary is that they are cheap so you could try one or two of them and if you don't like them it's not a lot of money wasted. The problem is, because they are so cheap, people tend to buy loads, slap it all on their face at the same time and wonder why they have a bad reaction.
I don't use their vitamin c, but I use Garden of Wisdom 23% vitamin c in the morning, before moisturiser and spf. It's about £10 or something and I buy it from Victoria Health. I know there are Vitamin C serums that go up to £80, or £100 or more
no way I'm spending that on one product.
Once you start looking into it, it can seem a bit overwhelming with all the ingredients and formulations. I suppose it depends on your level of interest; some people just want a very simple routine of cleanse and moisturise, others have 20 different potions at the ready.
You could try introducing the vitamin c for a few weeks and see how your skin reacts, and then try an AHA for exfoliation, or a retinol (but that will take a while for your skin to acclimatise to). Most good moisturisers also have hyaluronic acid in them, I use Cerave moisturising lotion, as it's fairly cheap from Boots.
I only started a few years ago, after noticing my skin getting dull and a few fine lines were appearing. I didn't want to go down the botox/ fillers route so I researched good skincare, and I'm really happy with the results. However, I know that everyone's skin is different , and what works for me may not work for everyone.
That being said - vitamin c serum, retinol, AHA's all have good results if you use them properly. Unfortunately, there is no miracle cream that does everything
but there are some really good ingredients that can help improve your skin massively.