On radiator & coolant:
If you're changing the coolant anyway (which is a good idea for a newly purchased used car of any type, see all the above posts) then at least go for a can of radiator flush to help remove any scale or rust or grunge or whatever that's in the radiator and other coolant passages. For a couple of bucks you get a can of stuff: add it to the coolant through the radiator cap, run the engine for a bit, then drain it. Refill with a mixture of antifreeze and water. Your choice of antifreeze depends on who you like to listen to; people will swear by all sorts of different stuff. I use 50/50 of the green stuff (ethylene glycol) and water. You could remove the radiator and have it professionally serviced, but I'd save that for the future when you decide you have cooling problems. Yes, everyone has cooling problems sooner or later, it happens to the best and worst of us.

On oil:
Heh heh. Perhaps the most over-debated topic on this forum, oil. Consult the owner's manual, if the car still has it. It'll probably recommend two different types, depending on your ambient temperature. THE FOLLOWING IS MY OPINION (and you know what they say about opinions): I personally use Castrol 20W50, since I live in a hot climate. If you're in a cold climate, you might choose a lighter weight, such as 10W40. As TXBill mentioned, synthetic probably isn't necessary. Perhaps ask the current owner what he/she uses, then just continue to use that. In my opinion, changing the oil regularly (every 3000 miles) is more important than pulling your hair out deciding between 20W50 versus 10W40.

On brake/clutch fluid:
I assume it's manual transmission, since you're asking about clutch fluid. The brake & clutch use the same type of fluid (DOT3 or DOT4 brake fluid). In my car (240D) there are two separate compartments in the same reservoir. In any case, you MUST change the brake fluid if the car has been sitting for a long time! Brake fluid will absorb moisture from the air, which changes its properties and may significantly affect your braking performance. It's generally a good idea to change brake fluid once a year, and make sure the system is closed properly otherwise (i.e. a tight-fitting cap on the fluid reservoir, etc).

On power steering fluid:
Power steering fluid is an easy change, approximately the same as changing motor oil. A little plug on the bottom of the steering gearbox opens up to drain the fluid, then you simply refill from the top of the power steering pump. If you change the power steering fluid once, you probably won't have to worry about it again for a long time. Worst case scenario, at least check the fluid level (just look in the top of the pump to see) and top it off if necessary.

Other stuff:
Like TXBill said, hoses are a subjective check to see if they need replacing. If they look OK they're probably OK. Haynes/Chilton's will have signs to look for on deteriorating hoses.

Belts are another subjective thing. My opinion: change them every few years or if you're doing other major work on the engine. Losing a belt won't stop the engine, at least on my 240D. If, god forbid, a belt breaks, you'll just have to drive without that component (power steering, alternator, or A/C compressor) until you can put on a new belt. I drove around for three days without an alternator while having it rebuilt.. By the third day I had to get a jump-start to get going, then didn't have lights or radio once I was on the road, but the diesel engine doesn't care if you have electrical power or not. Anyway, I digress.

Unless you have record of the last time the valves were adjusted, a valve adjustment is a good idea. Then, every 10,000 miles. It's a pretty easy job if you have the right tools. If the valves aren't adjusted perfectly, the engine wil still run. Properly adjusted valves will give better performance - that is, less black smoke and more power.

Air filter and fuel filter(s) - perhaps the easiest maintenance you can do.

I can't think of anything else right now. That's all I would do initially if it were me. Of course, there may be other things that you'd notice .. new tires if they're bald or obviously deteriorated, new battery if it won't hold a charge, etc.. but those all depend on the condition of what's on the car now.

- Nathan
'83 240D, 255k miles
'00 New Beetle TDI, 27k miles