Cold, dark, misty and lost
Should you ever venture into the wilderness at night and decide to get lost, be sure to take a tent, a torch and, above all, an interesting book.
There is nothing worse than getting lost on the Scottish moors in Winter, only to find you have nothing to read.
Maps and compasses are all very well, but they take up valuable space and are pretty low in entertainment value.
Also, and very importantly, a powerful battery is required. With around sixteen hours of darkness, it would be jolly irritating to reach the final chapter of "Kidnapped" or some other rivetting read, only to find one's battery is getting low.
Remember, as mobile telephone coverage can be patchy in many areas, it may not be possible to phone anyone before you perish, to find out how the book ended.
Finally, I would also advise the inclusion of a couple of Mars Bars. These might allow you to concentrate on those final chapters, as the intense cold saps at your rapidly-dwindling energy reserves.