Chris,

Thank you so much for your quick reply. I agree with you that I have to keep the amount of poly low but this game is not cartoon related or so. You can really build realistic buildings (the outside view). I have to create the buildings in Maya (3ds or C4D works also) and then export all the stuff with an exporter plugin created by the game engine developer.
If i put just a texture from an image it is not the same as a really realistic texture (material?). I don't want only to modeling for this game but also for my pleasure and improve my skills in Maya and other 3d software.
Thank you for the hints. I will give them a try, but if there are good tutorials for this kind of work, please let me know!

Many thanks Chris.

Lecra