Turn a map the wrong way up and it stops being useful and becomes a puzzle. Yet the skills involved are small and learnable: matching the paper to the ground, reading a grid reference, walking on a bearing without drifting into the wrong valley. Give it an afternoon on familiar ground and the whole thing clicks into place. Here is how to build those skills from scratch, with a paper map and a baseplate compass.

What the map is telling you

Most people in Britain start with an Ordnance Survey sheet: Explorer at 1:25,000 for detail, Landranger at 1:50,000 for broader coverage. The two features beginners skip are the most useful ones — the legend and the scale, both printed in the margin.

Scale is simply the ratio between paper and ground. On Explorer, 4cm on the map equals 1km on the ground. On Landranger, 2cm equals 1km. That matters when you are judging whether a footpath shortcut saves you time or lands you in a bog at dusk. Most compass baseplates have a ruler or romer printed on them, so you can measure straight off the sheet.

Contours: the third dimension

Contours are the brown lines. Explorer sheets space them every 5m of height, Landranger every 10m, with occasional thicker lines carrying a number. Lines packed closely together mean steep ground; wide spacing means gentle. Where a contour forms a V, the point of the V aims uphill — so a V shape crossing a valley floor marks a stream running down towards you. A useful exercise is to find a hill you already know well and trace its contours with a finger. You will start to see the shape of the land rather than flat paper.

Grid references without the panic

The blue lines across the map are kilometre squares. Numbers along the top and bottom are eastings — they increase from left to right. Numbers along the sides are northings — they increase from bottom to top. The rule to memorise is eastings first: along the corridor, then up the stairs.

A four-figure reference such as 6521 puts you somewhere in a 1km square. Add two more digits and you narrow it to 100 metres. So 654219 means: go 65.4 grid lines east, then 21.9 north. In practice you read to the nearest line to the left of your point, then estimate the tenths across the square. Your compass romer does that part for you.

Try it at home. Pick a footbridge, a church with a tower, and a spot height, and write each one as a six-figure reference. Then hand the list to someone else and see whether they find the same features.

The compass and its parts

A baseplate compass has five things worth knowing:

• Baseplate and direction-of-travel arrow — the long edge you line up on the map, and the arrow that points the way you intend to walk.
• Bezel — the rotating housing marked in degrees from 0 to 360.
• Orienting arrow and lines — the markings inside the housing that you align with the map's grid lines.
• Magnetic needle — the red end points to magnetic north, when the compass is flat and still.
• Index line — the mark where you read your bearing.

Keep the compass away from anything magnetic: phones, car keys, fence wire, an iron gatepost. A metre or two of separation is plenty. Hold it flat in the palm, level like a plate of soup, and let the needle settle before reading anything.

Taking a bearing from the map

1. Lay the compass on the map with its long edge joining your position to your destination, and the direction-of-travel arrow pointing at the destination.
2. Rotate the bezel until the orienting lines inside sit parallel with the vertical grid lines, with the orienting arrow pointing to the top of the map. Ignore the needle completely at this stage — it has no opinion about the map.
3. Read the number at the index line. That is your grid bearing.
4. To convert it to a magnetic bearing, allow for the difference between grid north and magnetic north. In Britain this is currently only a few degrees, but it changes over time, so check a current figure rather than trusting the note on an old map.

Following a bearing on the ground

1. Set the bezel to your bearing and hold the compass flat in front of you.
2. Turn your whole body until the red end of the needle sits neatly inside the orienting arrow — experienced walkers call it putting red in the bed.
3. Look up and pick a landmark in line with the direction-of-travel arrow: a boulder, a lone tree, a bend in a wall. Walk to it without staring at the compass.
4. At that landmark, check the needle again and pick the next one.

Three or four cycles of that will carry you a long way over rough ground. Add two habits and you will be more accurate still. First, aim off: if you are heading for a bridge on a stream, deliberately aim slightly to one side of it, hit the stream, then follow the bank to the bridge. Second, pace: count double paces — one count for every two steps — and measure your own count over 100m on flat ground before you rely on it. Most adults land somewhere in the sixties, but it is worth knowing your own figure, and it grows on hills.

Three exercises worth an afternoon

• Orient the map. Stand at a path junction. Put the compass on the map, align the orienting lines with the grid lines, then turn the whole map until the needle lines up. Features on the paper should now match features around you.
• Reverse bearings. Walk 300m on a bearing, then work out the back bearing — add or subtract 180 degrees — and check that your starting point lies on that line. It is an easy way to catch a drift before it becomes a detour.
• Use handrails. Plan a short route that follows a wall, a stream or a ridge for most of its length. Handrails reduce the number of decisions you make, which is exactly what you want in poor visibility.

Before you set off: a five-minute routine

Check the map's edition and the current magnetic variation. Fold the sheet so the relevant section shows, and keep it in a clear case on a lanyard rather than stuffed in a pocket. Identify a catching feature — a road, a river, a ridgeline — that tells you when you have overshot. Tell someone your route and your expected return time, and carry the paper map and compass even when your phone is charged; batteries fail fastest in the cold, and a phone screen is a poor substitute for a sheet you can read with gloves on.

Then go and practise somewhere small and familiar, in good weather, with a short route you could walk without any of it. The point is to make the movements boring. Once the mechanics are automatic, you can spend your attention on the ground in front of you, which is where it belongs.

Photo: MarandaP / Pixabay