A simple shelf is one of the best first projects in woodworking. It teaches you the three skills that underpin almost everything else — measuring accurately, drilling cleanly and finishing properly — yet it costs very little and you can put it up on the same afternoon. Get this one right and you will have a shelf that holds a surprising amount of weight, sits dead level and looks like it belongs in the room. Get it wrong and you will have a sagging board, four holes in the plaster you did not want and a renewed interest in flat-pack furniture. The instructions below describe a 900mm shelf in 150mm x 25mm pine, fixed to a wall using a hidden batten. That gives you the clean, floating look without any visible brackets.

Choosing Your Timber and Gathering Tools

For a first shelf, straight-grained pine is forgiving and inexpensive. Choose a board that is already planed and square-edged, and take a few minutes to sight along its length before you buy: if you can see daylight under a straightedge, it will twist once it is on the wall. Avoid timber with large knots near the ends, as these weaken the board where you will drill. For the concealed batten, ask for a length of 50mm x 25mm pine cut to about two-thirds of the shelf length. Anything shorter and the shelf will flex at the ends. You will need:

• A tape measure, pencil and a 600mm spirit level
• A fine-tooth saw (10 to 12 teeth per inch) or a tenon saw
• Drill bits in 3mm, 6mm and 8mm, plus a countersink bit
• Wall plugs and 4mm x 50mm screws for the batten
• Four 4mm x 30mm screws to fix the shelf down
• Sandpaper in P120 and P180 grits
• Wood filler, plus a primer and a durable topcoat, or a hardwax oil
• A cable and pipe detector

That last item is not optional. Before any drill touches the wall, run the detector across the full width of where you plan to fix, at both the top and bottom of the shelf position. Water pipes and cables rarely run where you expect them to.

Measuring and Marking Out

Decide on the height first, then measure from the floor rather than from the ceiling, skirting or any other feature — floors are the reference point you can trust. Mark lightly in pencil at both ends of where the shelf will sit, then hold the spirit level against both marks and draw a single line between them. Now check your line with the level in both directions before you do anything else. A shelf that is 3mm out over 900mm is immediately obvious to the eye, and no amount of clever styling will disguise it. If your marks disagree with the level, trust the level and re-mark. Once the line is confirmed, hold the batten in place along it and mark through the batten's pre-drilled holes — or simply mark your fixing positions at roughly 100mm in from each end and every 300mm between. Three fixings are plenty for a shelf of this length.

Cutting and Sanding the Shelf

Cut the board to length on a workbench or across two trestles, supporting both sides of the cut so the offcut does not drop away and splinter the edge. Let the saw do the work rather than forcing it, and keep the blade vertical by watching the line on the front face rather than the top. Sand the cut end with P120, then work along the whole board with the grain — never across it, as cross-grain scratches are almost impossible to remove. Finish with P180. Run a piece of sandpaper lightly along the front arrises to soften them and take away that sharp, freshly sawn feel, but do not round them over; a crisp edge is what makes a shelf look properly made.

Drilling Pilot Holes and Fixing the Batten

Pilot holes stop pine splitting and keep your screws running true. As a rule of thumb, use a drill bit roughly the same diameter as the shank of the screw — the solid part, not the threads. For a 4mm screw, a 3mm bit is about right. Drill through the batten, then countersink each hole so the screw head sits just below the surface. Drill the wall at your marked positions with the 6mm or 8mm masonry bit, depending on the plugs, and go about 10mm deeper than the plug length so dust has somewhere to sit. Push the plugs in flush, then screw the batten to the wall and check it with the level again as you tighten each screw.

Attaching the Shelf and Finishing Up

Set the shelf on top of the batten and check the overhang is even at both ends. Drill 3mm pilot holes upwards through the underside of the shelf into the batten, then drive your 30mm screws up from below. Nothing is visible from the front, which is exactly the effect you want. Fill any small gaps where the shelf meets the wall with a bead of decorator's caulk, wipe it smooth with a damp finger and let it dry before painting. Finish the shelf itself with two coats of primer and a satin topcoat, or a hardwax oil if you prefer the natural grain. Leave it to cure fully before loading it up — a few days for paint, overnight for oil.

Common Mistakes to Avoid

• Drilling without checking for cables. Always use a detector first, every time.
• Skipping pilot holes. Pine splits easily, and a split end means starting again.
• Over-tightening screws. Stop when the head bites; extra force only strips the hole or pulls the batten out of shape.
• Sanding across the grain. It leaves scratches that show up badly under paint or oil.
• Putting heavy items on before the finish has cured. Give it the time it needs.

Once it is up, stand back and check it from across the room. If the line looks level and the edges look clean, you have done the job properly — and you have learned skills you will use on every project that follows.