I am also relatively new here, 3 yrs, and this site has been very helpful to me. Mine sat under a maple tree for 6 years, so I have had to do about everything so far.
Here are some words, but not sure about the "wisdom."
Don't know if you have any service records, but if you don't, you will want to do a few things.
Change the oil to a 5W-40 that meets Mercedes spec 229.5. This site lists all the "MB Approved" options. MB 229.5 - Multigrade engine oils (Specification 229.5) - Mercedes-Benz Specifications for Operating Fluids
I personally use Amsoil 5W-40 Euro "classic", which is on the list above. It is a true "Full SAPS" oil, which this car wants. See info here: AMSOIL European Car Formula 5W-40 C-ESP Synthetic Motor Oil
Liqui-Moly Leichtlauf High-Tech 5W-40 is another that I will try soon when my oil stash runs out.
Beware using oils that have the newer MB 229.51 approval. I tried Mobil 1 Euro 0W-40, and the car has used a little oil this time, and never did on the Amsoil, so I will be going back. May be a coincidence, but it never used a drop for 2 years with the Amsoil.
M1 Euro is OK for cars that can use the 229.51 Low SAPS formula, like my 99 CLK320.
Good Oil filter options are Mann W719/13, Mahle OC110, Hengst H14W40, WIX 51088. Amsoil makes a long-life filter that is more expensive, EaO34, if you want to try longer oil change intervals.
Change the fuel filter under the center of the car.
Take a look at the coolant. Your engine has a history of head gasket failure. Look for oil in the coolant, or if the engine oil looks like chocolate milk when you drain it. Flush system and refill with distilled water and either MB coolant or Zerex GL-5. Be sure that you have the heater on to open the valve to the heater coil for the flush and fill.
Run a good fuel injector cleaner through the gas tank. Amsoil PI is one good one. I ended up replacing my injectors after a year and it made a big difference.
And be sure to use 93 octane fuel.
Check the air filter. According to many, the air filter is more important for keeping the OIL clean than the oil filter is!
I just change the shocks on mine in the last year. Made a big difference in cornering and brake dive. An easy DIY project, I thought. Some of the bolts are a bear to break loose.
I bought KYB brand, because they were cheapest for a car that age, but it is a firm ride. Bilstein and Sachs/Boge are more "standard" OEM replacement, and not much higher $$.
Pull the spark plugs and see how they look.
Take the distributor off and see how much wear there is on it and the rotor.
For me, everything looked original at 120k miles, so I changed cap, rotor, plugs, plug wires. Another easy DIY.
Good luck, and don't be afraid to ask questions.
Use the search feature. Most questions have already been asked.
They are great little cars!