Front: Jack under the tubular crossmember, axle stands either under chassis rails or at the front corners of the floor, if you are sure they are not rusted.
Back: Renault provided a special trolley jack fixing that was placed under both boot floor chassis rails, but as no one is likely to own one nowadays, it's not practical to jack both rear wheels at once. Jack is placed under scissor jack points and axle stands under boot floor chassis rails where they meet the rear crossmember, or vice versa. Another secure point for axle stands is under the outer suspension arm mountings, provided that you don't have to remove a suspension arm, and the chassis is solid at this weak point.
