The best way to shade your windows depends on which way they face, because the height and angle of the sun changes as it moves through the sky and as the seasons change.
South-facing windows receive almost no direct sunlight, so they don't require shading in summer. However, cooling breezes in summer usually come from the south so these windows are useful for cross ventilation. South-facing windows will lose heat from the house in winter unless well protected with either double glazing or heavy curtains and pelmets.
During summer, east-facing windows can be a major source of heat gain in the morning, while west-facing windows can be a major source of heat gain in the afternoon.
Adjustable external shading devices such as blinds, awnings, louvres or shutters, or angled metal slats provide the flexibility to block the low-angled morning and afternoon sun. Adjustable shading devices allow greater flexibility to make adjustments on a day-to-day or even hour-by-hour basis, in response to changing weather conditions and comfort levels.
Eaves, pergolas and even verandahs provide some benefit, but are not very effective at shading east and west windows as they do not block out the lower-angled early morning and late afternoon sun in summer. If you have a verandah it may be possible to install blinds on the perimeter to shade the windows, walls and verandah itself, making the whole area more comfortable in summer.
Windows that face north-east and north-west are also best shaded by adjustable vertical shading devices such as awnings or blinds.