LONG-handled rollers, plastic sheeting, and why you emphatically shouldn't just trust your judgement when picking a colour. By Luke Rix-Standing.

In the pantheon of DIY tasks, painting a wall is not one of the trickier ones. There's a lot of setup, a few must-remembers, and more-than-expected physical exertion, but otherwise it's low-level stuff.

Unfortunately, what painting lacks in difficulty, it makes up for in risk. Your walls are your home's desktop background and screensaver rolled into one, so when it comes to do-not-want-to-mess-up factor, room painting ranks alongside replacing your front door.

So, if you need or want to repair your paintwork, renovate a property, or just refresh your rooms with a fresh colour, here's everything you need to consider. A good coat of paint is about 90% preparation - don't say you we didn't warn you.

1. Consider your colour

What the sky is outside, a paint job is inside (and just think how much weather can determine mood), so you need to think carefully about your desired tone. Brighter colours can be energetic and invigorating, while more muted shades are softer, more atmospheric, and less assertive.

"If you're nervous about your colour scheme, start with neutral colours inspired by nature," says Marianne Shillingford, creative director of Dulux. "Clay, stone, sand and wood work with each other and every other colour, so can be the bedrock of any decorating scheme. Use bolder colours in smaller amounts on furniture and skirting boards to help bring the room to life."

Deeper shades can be rich and rewarding, but they do shrink a room and require a certain amount of management. "Using dark colours can work in places we want to be grown-up and relaxed," says Shillingford. "The key is to use layered rather than overhead lighting, and on all walls not one or two."

You can even mix up your colour scheme; slapping some colour onto an 'accent' wall can brighten up a room that's playing it safe. It's common to paint ceilings a lighter hue though, to avoid any feeling of claustrophobia.

2. Mistrust your judgement

We don't want to point any fingers, but your main danger may come from your own conviction. "The biggest pitfall," says Anita Mullane, colour consultant for Colourtrend, "is that customers go into the shop, pick a colour, get it mixed on the spot, put it on the wall, and find that it's completely wrong.

"Lighting is huge," she adds. "In store, you might have bright, white light shining down on it, which might be completely different to the light you have at home. Take a tester pot home, paint an A4 card (two coats), and then move it around at different times during the day. Take it into dark corners and lighter areas so you can see how the colour changes."

The colour may change further in different rooms - depending on orientation. North-facing rooms will get a lot less sun, while south-facing spaces may be lit in abundance. This changes with the seasons too, and you want to be as happy in the blazing sun, as you are curling up in the depths of winter.

Finally, consider any given room's function before you charge in. "A kitchen is a workspace, and generally you want workspaces to be brighter," says Mullane. "The living room on the other hand, might be somewhere you retire in the evening, so perhaps prioritise something more chilled out. In the bedroom, deeper colours often allow you to sleep better."

3. Prepare your surfaces

First of all - and we can already hear the groans - you're going to have to do some cleaning. There's not much point redoing your living room if the paint flakes within a week, so give your intended surfaces a thorough dust and wash them down with sugar soap.

Allow the soap to sit for a few minutes, then do a wipe-down with clean water. Sugar soap can irritate the skin so wear rubber gloves, and don't let it drip in your eyes when cleaning the ceiling.

If there are holes, cracks or imperfections, now's the time to marshal them. Most commercial fillers will do the trick - take advice if you're uncertain - and leave time to dry before moving on. Next smooth down unwanted protrusions with medium sandpaper, and give the whole surface a once over. The slight roughness that results helps improve the paint's grip.

This process produces fine dust, so don a mask. When you've finished, you'll need to vacuum the whole room (yup - the ceiling too). Dusty paint is not a good look.

4. Don't be a mucky pup

Room painting is a messy business, and you'll need to paint-proof your furnishings from splash damage. If you can, empty the room entirely, but if that's not possible then create a pile in the middle of the floor that you can cover with dust sheets or plastic.

Remove or cover light fittings and door handles, and use masking tape to protect the edges of doors, windows, sockets and skirting boards. Finally, don't skimp on the drop cloth - however dexterous you are, paint will splatter.

Running out of product part way is a right pain in the paintbox, so measure the area of your walls to ensure you buy enough.

Otherwise, you need brushes and rollers, and if you're doing the ceiling then a roller on a pole too. It's worth investing in high-quality products, as hair coming out of your paintbrush halfway through can really ruin your finish. Consider picking up an angled brush as well - it helps reach those awkward corners.

5. The moment of truth

So, you've picked your colour (and tested it rigorously), you've cleared your schedule and your floor space, prepped your kit and scoured your surfaces... Can we finally start painting now, please?

If you're repainting the ceiling, always do that first. Begin by 'cutting in' - using a brush to create bands of paint around obstacles like light fittings, and along the edge where ceiling meets wall.

Now the moment you've all been waiting for. Fill your reservoir tray about a third-full of paint, roll paint onto the roller and go to town - no wrong answers. If you're doing more than one coat, let the first coat dry - a la the instructions on the pot - before applying the next one, and make sure you've finished the ceiling before turning to the walls.

Painting walls is much the same, if a little less knackering. Use a shorter-handled roller that's easier to manoeuvre. Clean up, refill the room, survey your handiwork, and hope against hope you haven't painted over a light switch.