If you want something less fussy than net curtains - and these days most of us do - how about frosted window film? This film is sticky on one side and gives a smart, contemporary finish both inside and out.
The effect is the same in daylight and at night when the light’s on in the room, giving you total privacy. The only real disadvantage is that you can’t see through the film, so while people outside can’t see in, you can’t look out either.
Frosted film works well on sash windows when confined to the lower window, but if you don’t have sashes, you can just frost the lower part of the glass, leaving some unobscured. Another option is having a design, such as rows of cut-out circles or squares, incorporated into the film, which makes it more interesting and allows you to see out (and people outside to see in) just a little. However, patterned film is more expensive and harder to fit.
Blinds are another popular and obvious solution to privacy problems. Although quite costly, bottom-up blinds are the best ones to use. These are roller blinds that go up from the window sill, rather than down from the top of the window, so you can cover as much of the glass as you want. Go for a sheer fabric and you’ll be able to see out, but not the other way round (unless the light’s on).
Some people like Venetian blinds because they give privacy during the day (providing the slats are angled the right way) and at night (providing the slats are closed). That said, plantation shutters, which are similar but look more elegant and up-to-date, have become more popular than Venetian blinds in recent years.
Plantation shutters are fitted to the window and this means they block out more light than blinds when the slats are closed (providing the shutters cover the whole window). However, they let in less light when the slats are open because they have frames around them. These shutters come in panels, so you can fold them back out of the way, and are made of wood or faux wood in different designs. Although not cheap, plantation shutters will enhance the room and can even add value.