Wall art placement.
Home interiors have no shortage of rules: Kitchen countertops are 36 inches from the floor and 24 inches deep. Deviate from this during a renovation and you'll be unpleasantly surprised: Your dishwasher won't fit and your cabinetry costs will shoot up 40 per cent for additional materials.
But there are ways in which obeying rules will also lead you to an unhappy - or, at least, bland - place. Guidelines make sense because they ensure that a home is functional, safe and cost effective. But after construction there are furnishing plans to draft, sofas to select, and light fixtures to install. And this is where the tension develops between needing a formula and being constrained by one.
Colour theory, clearances, and furnishing genres: it's important that you first know them, of course. No one who has neglected to learn his piano scales can go on to play free jazz. But once you're fluent in the rules of decoration, you'll know better which ones you can afford to challenge and break.
Here are four I suggest you play with.
Paint one feature wall a bold colour
I'm not sure when the feature wall became part of the decorating vernacular - it's been around for a while - but I suspect it rose steeply in popularity with the 90's television show "Trading Spaces."
The principle at work is a good one. A feature wall is intended to be a "pop" - a tool to direct your gaze to one part of the room. The problem is that the notion is now shopworn from overuse
Break the mould by taking a deep breath and painting the entire room the colour you'd intended for the feature wall. Using a rich hue - sapphire blue, say - takes courage but the results will be transformative.
It will jar the eye at first, but it will give you fresh eyes for your home. And with that new perspective will come the motivation to make changes to integrate the blue - new drapery, new art, perhaps some bluey accents in other areas of the home.
A radical change in one room can catalyze a change everywhere and revitalize a tired interior.
Use a symmetrical furnishing plan
The scientists tell us that the main way humans judge attractiveness in people is by symmetry of features - everything on the left side of the face is identical to the right side. It's supposed to be an indication of genetic superiority.
Symmetry - or, at least, balance - is as safe a bet in furniture arrangements as it is in mates. You buy matching pieces and oppose them in your well-planned living room - a beige sofa on one side of the fireplace, two chenille armchairs on the other, and a glass coffee table in between. Ah, perfection.
You know how when you go to an all-inclusive in Nuevo Vallarta, and the beach is spotless, and everyone's smiling, and the buffet always opens at the same time, but, curiously, when you think back on the vacation, you have a hard time remembering specific details - nothing stands out? Welcome to your living room.
Lots of forgettable mates have perfect faces, and lots of competently designed living rooms could afford to have their symmetry rearranged. A great way to break the mould is to buy good large-scale pieces that have an enduring profile, like Baldwin sofas or Saarinen dining tables.
Then, dial up the contrast with vintage chairs, accent tables and lamps - and don't worry if they're not perfect matches. The different ways in which the pieces are in conversation will keep things interesting.
Above all, remember that not everything needs to line up.
Hang your art at 54 inches on centre, in the middle of a wall run
The 54-inch rule is a good starting point for single pieces but the practice, if you abide by it unwaveringly, threatens to make your home look like those people whose photographs come inside a store-bought picture frame - pleasant and noxiously generic.
There are a few ways to break the rule. You can fill entire walls with an eclectic collection of artworks - those inherited from family, cherished drawings from your kids, and so on. The mix-and-match approach makes a room engaging and authentic.
If you like things sleek and sophisticated, an oversized painting (floor to ceiling) makes a spectacular backdrop for a dining room. Or, if you prefer a bit of quirk, hang a series of common-sized prints in a column (nearly floor to ceiling), offset from the centre of a large wall. The odd placement will challenge people's expectation of symmetry and infuse the room with visual tension.
The idea is to do something unexpected rather than keeping all your artwork on the same plane. This encourages your eye to travel around the room and keeps you engaged in the space.
A chandelier's size should be one-third the length of your dining table
This rule stems from a broader law about proportion - the rule of thirds. You divide a room's proportions by thirds to design the wall elevations. For example, floor-to-ceiling cabinetry in a library usually has closed storage on the bottom third and open shelves on the upper two-thirds. It's an issue of visual balance.
I employ this rule in every home we design, but I also like to play with it.
In the case of chandeliers, following the one-third rule too closely can make the fixture look like a token choice. An over-scale chandelier - anything up to two-thirds of your table, really - will instantly give the room drama and glamour.
As in other areas of life, in interiors, rules save us from unnecessary trouble. But it's possible to get too caught up in them. Learn your design scales, by all means. But don't let them get in your way of playing a few challenging, disruptive or seductive notes.