You can put the jack under where the jacking points are on the side. The jack stands can also go there. You can jack the rear at the differential. In the front there is a reinforcement that goes across under the engine from side to side. You can jack the front there. www.pelicanparts.com
also sell a jack pad that goes into the jacking points on the side of the body. Slide them in, use a floor jack to jack up the car, and put your stands under the jack points for support.
1995 325I, window tint, K&N, debaffled airbox, BMW #104 wheels, Nighthawk low beams, smoked side markers, smoked corners, smoked taillights, M3 stlye heated mirrors, various interior bits, Bosal cat-back.