The following suggestions are a compilation of what seem to be the best ways to combat the most typical failure items:

Modify the motor mounts to decrease the amount of travel.  See the motor mounts section on the Repair Procedures page.   Inspect the mounts every six months or so and repair any failures quickly to prevent  damage to other mounts.

Don't push the automatic transmission.  As much as possible, avoid forced downshifts and  kickdown shifts.  As much as possible, allow the transmission to shift up when it wants to and avoid full throttle shifts.  Change the filter and fluid regularly, using multiple fluid changes with a siphon pump to remove as much of the old fluid as possible.

Use Bar's Leaks (liquid, in the silver bottle) in the cooling system, renewing every six to twelve months.  Backflush the cooling system and renew the thermostat, coolant and Bar's Leaks every 24000 miles.  Bar's Leaks Web Site  These measures should prevent heater core and head gasket failures. 

Use the stock Saab-specified spark plug, properly gapped.  For 2.3 liter engines (all 2.3 L engines have Direct Ignition), replace the plugs at least every 30000 miles and re-set the gap every 10s000 milesUse dielectric grease on the sparkplug boots (Prestone makes this stuff, so it's easy to find).  This should keep the plugs within the specified gap range (.039" to .043") and the engine should never miss a lick.  Avoiding over-gapped plugs and plug body-arcing, and the attendant misfiring, appears to prolong the life of the $300 D.I. cassette dramatically.  One board participant reports 183000 miles on his DI cassette without a failure.  Conversely, my local Saab dealer told me that poorly maintained cars have had DI cassette failures in as few as 50 k miles.

Have the air conditioning system serviced yearly.  This should prolong the life of the AC compressor. 

 Keep the air conditioner evaporator drains clear (see the Procedures/Repairs page).  This will help prolong the life of the blower motor and its controller, because clogged drains will allow collected water to slosh up into the blower vanes and overload the fan motor and controller.

Change the brake and clutch fluid (DOT 4 fluid only) every two years.  This helps to protect the clutch master cylinder and the very expensive ABS parts.

Flush and renew the power steering fluid (genuine Saab or General Motors power steering fluid) every  24000 miles (see the Procedures/Repairs page).  Should prolong the life of the steering rack and pump.

I still believe that the use of synthetic oil will provide far better protection for the engine and will prolong the life of all its moving parts.  I firmly believe that its high heat tolerance makes it a must for turbochargers.

Inspect the CV joint boots regularly (see Maintenance checklist).  Replacement of cracked boots (before they split) should virtually eliminate CV joint failures.

Inspect the serpentine belt, idler pulleys and crankshaft pulley regularly.  This should prevent expensive and extremely inconvenient  breakdowns and additional damage due to failures of some relatively inexpensive parts.

Perform maintenance regularly.  This accomplishes everything in this list, plus many more important items.  See the maintenance schedule in the Repairs/Disassembly section of the Procedures page.