Brilliant white skirting against a soft, muddy wall colour is the single most common mistake I see. It chops the room up, draws the eye straight to the edges, and makes a lovely wall colour look dirty by comparison. So unless you genuinely want the trim to be a feature, stop defaulting to stark white.
There are three approaches that actually work:
Tone-on-tone (my usual recommendation). Paint the skirting and architrave the *same* colour as the walls, just in eggshell rather than the wall finish. The room reads as one calm envelope, ceilings feel higher, and small rooms feel bigger. This is the trick behind most magazine-worthy spaces. Works beautifully with greys like Farrow & Ball Cornforth White or a green like Card Room Green.
A soft off-white that flatters. If you want contrast but white feels cold, use a warm, slightly knocked-back white. Farrow & Ball Pointing and Little Greene French Grey - Pale are both reliable — they hold their own against colour without screaming. Avoid anything with optical brighteners; they go blue-grey in shade.
A considered contrast. For period drama, take the trim *darker* than the walls — Down Pipe or even Off-Black against a paler wall gives a confident, architectural look that's far more sophisticated than white.
Whatever colour you choose, finish matters more than most people think. Skirting and architrave take knocks and scuffs, so use an eggshell or satinwood — Little Greene Intelligent Eggshell or Benjamin Moore Advance both go on smooth, level out nicely and clean up well. Prime any bare or knotty wood first with Zinsser BIN to stop knots bleeding through.
Practical tip: paint a test patch of your trim colour right next to the wall colour and live with it for a day or two. The relationship between the two is what you're judging — not either colour on its own.