Using light to design a home is trickier than you might think, because new technologies and regulations affect the type and number of fittings you can have in a domestic setting.

However, the results are worth it if you take the time to explore the possibilities. Gone are the days of thinking that a single light bulb in the middle of the ceiling would do the trick, especially in bathrooms and kitchens.

If you are carrying out major works, building an extension or even a new house your architect or professional lighting designer will help you, however, you may want to go it alone in which case there are a number of rules to follow that will make a considerable difference, whatever style your home will be.

There are four types of light to consider when you are planning the lighting in your home. These are natural, ambient, task and accent. To give your home depth and character you should try to incorporate all four in each area.

If you do go it alone your first task should be to get an accurate measured floor plan and mark the existing light fittings and sockets on to it. In the absence of professional drawings you can measure round the room and make a rough plan on graph paper, or use one of the many home design software packages around. Once you have plotted the existing fittings you should add your proposed furniture layout. The fittings should follow the layout, not the other way round, unless your budget is very tight.

Think how you hope to use the spaces, for example will you have living rooms which are also corridors? Can you see potential dark spots such as the turns on stairs? What sort of atmosphere would you like to create? Is the room to be brightly lit or have pools of light against a darker background? You would also be wise to read up on the topic - I find The Bible Of Home Lighting by Lucy Martin (Apple Press, £14.99) invaluable.

I mentioned technology. We all have to use the new, low-energy light bulbs. It is important that you look at your colour schemes in every kind of light. Combinations which work in daylight or with soft, old-fashioned tungsten halogen light bulbs will not look the same with LEDs. Colours which are wonderful in sunshine may change under low-energy down lights. It is a vital exercise to make sure that the colours you choose for each room work as well in the home as in the showroom.

Natural Light

It is important to maximise natural daylight, particularly with electricity bills as they are. Even with small windows there will be times of day when no electric light is needed. I am amazed how many people switch lights on automatically whether they are necessary or not. When you are thinking about the room layouts, would moving a chair close to a window make it easier to read without extra light? Can you make sure that you face a window when you want to iron, sew, cook or play? In a study or home office, putting the desk in the right place may mean that you do not need electric lights while you work. In my office, I only put the lights on when the daylight fades, and even then a single desk lamp is enough if I am at the computer - why waste electricity by switching on more?

Ambient light

This is the light which enables you to move around. Corridors and staircases should always be well lit. I have done a number of homes where step lighting (which washes down the wall) has been used to complement the ceiling lights. That is particularly useful if you want lighting to be left on at night in case people move around in the semi-dark (especially small children). I also make sure that bathroom lights are on dimmers, or that there is a low-level source of light. You don't want all lights blazing when you go to the loo in the night.

Task light

This is the one which enables you to do different activities such as reading, writing, cooking, sewing and dressing when natural light is not enough. Decorative table and floor lamps come into their own as task lighting. Think about the scale of the lamps and strength of the light bulbs for each task. A bedside light should be tall and bright enough to make reading in bed easy.

A light for sewing needs to be strong and as close to daylight as possible. Lamps for reading or playing games need to provide a good spread of light. I avoided floor-standing lamps for a long time because there were few good-looking ones on the market, but now I am a fan: they're so versatile.

Accent lighting

This leads the eye to the highlights of a room, giving it depth and atmosphere. Picture lights, bookcase and shelf lights, directional spotlights and wall washers all help you to highlight different areas and objects.

If you have a view towards a particular feature in the house can you light it so that it draws the eye? If you can it will make the home much more interesting. I always like to have directional lights over a dining or coffee table, which can highlight a centrepiece. Also, if you plan to have lights over a dining table, have wall lights and candles too. Nothing ages someone over the age of about 22 quicker than having light wash down the face from above.

Mary Leslie Interior Design, The Bothy, Rait Antique Centre, Rait, Perthshire. PH2 7RT.

01821 670776 www.mhleslie.co.uk