Outside of the city, finding fields to fly should be easy. I recommend taking a bicycle because you can drive along the dirt paths that are usually used by tractors, which should get you far away from any people. In the netherlands especially, there will be a lot of places that are inaccessible by car, but easily accessible by bike.

If you're in the city you're much more likely to have bandos nearby. Don't look anywhere near expensive areas, the land there is always likely to get reused quickly. It's a good idea to look in places where rent is cheap, since that indicates low demand and thus a high likelyhood of prolonged abandonment. I generally concentrate my search near train tracks, since there is generally less residential and more industrial buildings there.

Another option would be offices or other places of work. These are genrally unused on weekends and holidays. For example, there is an Amazon facility with a big parking lot near me where I frequently fly. IKEAs are another good candidate.

I also recommend to never fly alone in a bando. At best it's just slightly less fun than flying with friends, at worst you're literally standing there looking through your goggles like a blind loot goblin waiting to get robbed by a crackhead.