The question of the Surface Area:

In the urbanized areas most of the grounds measure around 300 m2, but a plot of 500 m2 will allow you for example to keep your distance with the neighbors, and to enjoy a spacious garden). On the other hand, a bigger ground supposes expenses and time for its maintenance, integrated in your search criteria.

The price is very variable from one region to another.  The demarcation of the land is very important to know the exact boundaries of your land and prevent any future litigation. Request a demarcation plan from the vendor and a survey done by a surveyor before purchasing.

Field conditions to check:

In any case, prefer a simple form, as close as possible to the square, to ensure optimal construction conditions.

It will always be better to buy flat land, to facilitate construction and to leave as many possibilities as possible. But a sloping terrain can offer other potentialities: greater surface area, better integration with the site, more unobstructed view, original landscaping. However, the construction will be more complex, and may require earthworks, foundation, water recovery, accessibility.

Beware of the pitches, or near a watercourse, they can present risks of flooding.

The nature of the subsoil is crucial:

All soils are generally heterogeneous, but one still distinguishes the good soils of the bad ones. The basement of your property must be stable and fluid to provide the foundation for your future home. Rocky or sand or gravel soils are considered good soils, the bad ones being those composed of clay, silt, embankments (risk of settlement, flooding, landslides). Attention also to the presence of a water table, old pipes, galleries or quarries buried (make a survey in case of doubt).

Subjective criteria but nevertheless very useful:

The opinion of the neighborhood, and the repeated visit to the place, is essential. Do not hesitate to discuss with neighbors about the environment, constraints, methods and construction choices, etc. And most importantly, visit the site several times, at different times of the day and week, to realize the advantages and disadvantages of the place and the environment.