This may be a little old fashioned but, here is my recommendations for an older than a mid 90's benz.
Minor service every 5000 miles including:
Check all your fluid levels and top up as needed.
Oil and filter. (Other say every 3000 your call)
tire pressures and tire rotation
Check suspension (Ball Joints)
Check your brake pads.
Check all your lights

major service 15000
the above service plus:
new plugs
check gases and adjust your lambda accordingly
new air filter
lub the door grease nipple and the door and trunk seals
new fuel filter
Valve adjust if applicable

Major service 30000 plus fluid flush
the above 2 services plus:
New transmission fluid and filter
new powersteering fluid and filter
Drain the Antifreeze (both radiator and block) and refill with new
drain and renew differential fluid
clean the brake resevoir and flush the fluid
Replace Filter and flush hydraulic suspension

I am sure I missed some stuff but here is a good start

m

__________________
Martin Ingram
Colorado Springs
2005 320 CDI
2006.5 VW Jetta TDI
1991 560SEL (179000 Sold)
1972 280SEL 4.5 ('The Lead Sled' 320000 miles when sold.)
1972 220D (225000 when sold)