Buying land is pretty easy.
Buying land should be tactical. On the one hand, you can try to get multiple contiguous properties to later build larger buildings by either buying 2 plots next to each other or building whole blocks (2x2, 2x3, 2x4, 3x3) to build mega buildings and thus more "influence" in the district and get correspondingly higher taxes.
The other option is to get land that has as many free neighboring properties as possible in the 7x7 radius. Theoretically, this can be up to 48 free neighboring properties. In reality, you should be satisfied with 30+. Background why you should have so many free neighboring properties is the following:
For each free property which is sold in your own 7x7 radius you get 12.5% of your own purchase price as a "tax" refunded. After 8 sales in your neighborhood you are equal (8 x 12.5% = 100%)
Example: A new district opens and you buy a plot in the 7x7 radius with no other plots of land have been sold so you pay the cheapest price and has good choice of the place all chances to earn good because you get now from all new neighbours "taxes "when they buy a property next to you. If you pay, for example, for your "virginal" plot 0,02ETH you get 12.5% "tax" directly to your wallet for every plot in his 7x7 radius . In this case, at 0,02ETH purchase price per new neighbor would be 0.0025ETH. 8 sales in the neighborhood and so you have your 0.02ETH own purchase price back.
(8 x 0.0025 = 0.02). Any further sale after the 8th neighbor can therefore be booked as a profit. Theoretically, 0.075ETH would be possible for a property with 30 neighborhoods. If one deducts the own purchase price of 0,02ETH then 0,055ETH remained as profit which either you can reinvested into new plots of land or hold on the wallet to construct buildings later.
It therefore makes sense always try to buy land not on the edge of a district but in the middle .