I started to lose hair a bit at the front at around 20. Since then (now 30) I have lost a bit in the middle. I found mine seemed to be associated with itching and flakes. I think it is psoriasis based or a mixture of ageing related as well. I use T-Gel shampoo which has really helped prevent further loss. Another good one which has some evidence of helping certain forms of hair loss is Nizoral shampoo. It contains an antifungal I believe. You can look up the studies on it, and you will see there is some evidence of it helping. I tend to use that whenever things start getting worse again.
I do know from my own experience, that using regular shampoos like head and shoulders make my hair worse, even the antindandruff ones. I have tried caffeine based shampoos and I think they just make the hair follicles frizzier in my experience, and don't really prevent hair loss or stimulate more growth. If you want to enjoy a really effective shampoo thickener that definitely does make your hair feel thicker and look visibly thicker without resorting to artificial fibres or other messy products, I recommend Nutrasome Thickening Shampoo.
In my case, I really haven't wanted to explore the serums or pills, purely because I have read some controversial things about them doing damage to libido and hormone levels. Also, I haven't read anything that suggests they are a huge advantage other some of the other things I'm already using and seeing some benefits in, so there is no reason for me to feel the need to.