Basement waterporoofing

Hello, I have a problem with a wet basement in the recently purchased townhouse. I am considering installing an interior drainage system (drain tiles) to help with the problem. I have 2 exterior walls and 2 walls that are separating my basement from my neighbors. I would like to know if it is necessary to install drain tiles all around the perimeter of the basement or just on the exterior walls. I am suspecting that water is also seeping around the footing of the walls that are not in direct contact with the soil. Does anybody have experience with this kind of installation? Any advice will be greatly appreciated. Thank you!