Please, the most important rule is to leave the common spaces as clean as you found them. / Para nosotros lo más importante es que dejes los espacios comunes tan limpios como los has encontrado.
Please wash your dishes right after using them. / Por favor lava tus platos inmediatamente después de usarlos.
If you cook, please notice that some oil or food can spill over the wall or around the hearths, so please clean it after use it. You will find cleaning products such as degreaser, etc.