Talk to me about home hair dying!

[MrsFogi]

So I have been having my roots done at the salon for about 20 years. I suspect I have a LOT of grey covered up under there. So, hypothetically, if we are going to be at home for months and, hypothetically, if I could get hold of hair dye what are my best options to look presentable (and not mess it up). In my youth I had very dark brown hair, I now dye it fairly dark brown. I have no idea where to start - I don't really mind whether I keep up the colour or just "manage' the grey with any colour that would make me look vaguely okay until the hairdressers open again (I have a friend who managed her grey with purple but this sounds like something that I could get very wrong).
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Can someone give me a 101 on home hair dye - I take it I don't just choose a random colour and hope for the best on the grey (I take it could end up a very different colour than intended).

Thanks

Is there any chance you can find out what colour your hairdresser uses? There is an early thread on here I think called "box dye" which is good. I use Wella Koleston 55/0 I am very dark brown / nearly black with white roots - I use Wella's peroxide and do a mix to cover the roots it's what my hairdresser uses for me and I've found it far better than box dyes. You need a mixing pot or an old bowl you don't care about and a dye brush if your hair is long consider a comb with a long tooth (pic attached) which will help you section and brush the dye into the roots. For dye that's gets onto your face use some facial toner on a cotton pad or maybe an old flannel and rub off it does take a bit of doing. Some people apply Vaseline around the hairline to stop the dye going on the face and ears etc.