There are products available to help conceal areas of thinning hair or small areas of patchy hair loss. These are commonly knows as ‘scalp makeups’ or ‘coloured hair thickners’.
They are really like a hair spray except they have colour in them. Part of the problem with diffuse hair loss is that you can see the scalp. These products are available in different colours so you match one to your own hair colour then you apply it and it colours your scalp the same colour as your hair.
This type of product is easy to apply. You would wash, dry and style your hair as normal and then section the hair using a sectioning clip or even a pencil and then spray the product on. if you spray it close to the scalp you will get a more pronounced colour, so start off by spraying it a few inches away. The product will wash out when you next wash your hair.
Using a product like this can be very effective. It is not suitable for large areas of hair loss but with diffuse thinning or small patches then it may well be a good cosmetic option. There are various brands available on the net but the one I know of is called Fullmore.