Needs to get winterized ...Oil changed,other fluids checked battery put on trickle charger or removed. Tires off the ground so they don't flat spot. You could put jack stands under the car just be careful where you place them. As for the interior. put some damp rid so you don't get any musty odors. You might put a box of baking soda and or charcoal inside this will help with odors also.
As for the engine...remove the plugs and put some oil on the top of the cylinders then put plugs back in. Fill the fuel tank so moisture won't form you should use a gas stabilizer. (ck to make sure it's compatable with your car ask a volvo service dept).Wash and do a good waxing of the exterior and I think that's about it.

96 850 WGN 39,000 Mi 89 240 DL