For starters, it helps to consider the existing colours in the room and use those colours as your guide. If there’s a particular piece of furniture or décor you’d like to match, find curtain colours that complement them. If you’re not so big on matching colours, neutral curtains are always a good choice.
In terms of fabric, one of the main criteria is the amount of lighting you want in the room. Sheer works well in complementing bright, airy, and open spaces. If you want to let some light in, but still have that slight dimmed feel to the room, go with linen. And then, of course, there are blackout curtains that provide maximum dimming effect by keeping almost all the light from entering the room.
And as for patterns, you might want to go with simple patterns—those that will remain aesthetically pleasing whether the curtains are open or closed.
These are very generic tips and if you want curtains that are customised especially for your home, consider getting bespoke curtains London with the help of kbcurtainsandblinds.co.uk.
