Don’t pick up a taxi right outside a tourist spot, i.e. the Topkapi Palace, as they will often not want to use the meter and offer you a flat rate. Walk a couple blocks over and find a taxi there. Make sure the light on the meter is not on for gece, which is for the night rate. I’ve never had that happen, but heard it could. I agree sometimes a route may seem like “the long way” when it really is not. I once thought a driver was doing this to me then had to put my foot in my mouth when he showed me the way I “knew” (which is the way I walked) was a one way street!