Directional is always best, in any type of aerial, TV WiFi, etc.. To set the direction just check the direction of aerials on the houses nearby or check the source of the WiFi signal.
When I need to use mine (TV or WiFi) I mount them on
ONE OF THESE with the cleaning bits stripped off and use cable ties to fix it the the rear ladder. They extend up to three metres and are way cheaper than
ONES LIKE THESE plus they are longer and allow cables to pass down internally.