So why a dark haired man? Well, this is thought to go back to the days when we didn’t like tourists that visited unannounced, stole our money/food/property and left us for dead. So a pale haired Viking knocking on your door just after midnight would not be a welcome guest.
Coal* was, and is now, seen as a symbol of good luck; however coal originally may have been more a symbol of warmth and the ability to cook a hot meal which would have been more useful a few centuries ago before central heating and electric ovens.
Whisky/Food was fairly obvious as a gift, it was the sharing of goods amongst the community but it could also hark back to the Pagan celebrations for New Year almost like a ‘bring a bottle’ arrangement for a party The type of food taken by a First-Footer varies depending on area. In the North of England for example it was usually bread, whereas other areas would have mince pies,  or black buns, or even fish.
Money was a sign of bringing wealth into the household, perhaps in the hope that they would then be prosperous throughout the year; salt could be taken in place of money as it was in the days before refrigeration a way of preserving food.

In some areas the First-Footer would shout or call out a traditional message such as “Happy New Year t’ye! God send ye plenty! Where ye have one pound note, I wish ye have twenty.” Though the message varies depending on the area. In other areas the First-Footer will say nothing at all until they’ve placed a piece of coal or the evergreen branch on the fire.

There are some First-Footing traditions which say they should carry some greenery with them, giving the greenery would ensure that the householders would lead a long life.

Another tradition associated with First-Footing would be that they should take ashes from the fireplace when they leave, this was removing the old year from the household and any associated bad luck with it.

Many elements have a Pagan Yule feel about them, and it looks like we could have modified another Pagan tradition into modern life, strange how often we do that.

Anyway, however you celebrate I wish you all a Happy New Year, if you hear someone knocking on your door just after midnight though, it won’t be me bearing gifts.

*As an aside, too carry coals to Newcastle (c.1600) Anglicizes the Greek γλαῦκ’ εἰς Ἀθήνας “owls to Athens.”