Keep it simple
Long, simple curtains are best. Attach with a plain pole and rings with a Brisby Pleat heading (soft, gathered pleats). If you want a bit of detail, you can add trim to the leading edge of the curtain.
Go for length
Curtains should touch the ground with a 1-inch break. In a formal or more ornate room, you may want to have a 3-inch puddle, which looks great with crisp, silk, ballroom-like curtains. Short curtains are only okay on a short window, and should still touch the window sill (such as café curtains – which open in the middle and are ideal in a bathroom or dressing room).
Splurge on labour, save on fabric
Curtains add vertical softness to hard, plain walls. They’re a good investment because the impact is so powerful – and usually necessary. The major cost is in the labour, and good labour is necessary, so make sure you’re hiring someone experienced to make the curtains. They should do a site measure, which will determine all measurements and fabric yardage needed. You can always save money on the fabric, as a pretty solid linen can be inexpensive and sill look terrific. Also, curtains need to be lined and interlined for fullness to look substantial as well as to block sunlight. The only time unlined curtains look good is when using a sheer fabric, for a wispy, summery look; otherwise, they look weak and wimpy.
Avoid vertical blinds
Curtains are a better solution for a long window since vertical blinds can look cheap and out-of-date.
You don’t always need curtains
For a simple, clean look in a bathroom, study or boy’s bedroom, try Venetian (horizontal) blinds or Roman shades alone. Or, use a café curtain on the lower half of the window and a soft Roman shade above for a pretty look when you don’t want to use long curtains.