Some buildings/apartments will not allow you to use them as a commercial let, so check the contract and sales details with the solicitor/ lawyer before signing. Also make sure if buying an apartment in a building if the contract is flexible which could permit your neighbor to convert his apartment into a bar, you may not want to live above a bar!
Also check that the plot of land you are interested in buying has the designation you need i.e. is registered for the building of commercial property (ground floor) and possibly apartments (habitacao) if you can build above ground level! There is currently a lack of commercial property readily available.
If you would like assistance locating something off plan please contact me.