1) No experience with that generation of Nissans, so take this with a grain of salt, but Nissan made some shit cars in the 80's and early 90's. Compared to what Honda and Toyota were doing, a lot of WTF design headscratchers and low build quality. But I guess every manufacturer has a bad stretch -- Toyota had some models in the late 90's and early 2000s that had notorious drivetrain problems (do a search for "Toyota sludge"). I have a Honda Odyssey model that is notorious for transmission failure (although not on mine...yet).
2) ANY used car needs to be checked-out by a qualified mechanic that YOU pay to inspect it. Preferably your mechanic, but if the car you are looking at is out of your area, find someone recommended from CarTalk or Angie's List websites, preferably a mechanic that sees a lot of that make and model. Even low-mileage cars can have catastrophic problems, like cracked-heads, bad engine mounts or electrical problems that are expensive to fix, but not immediately apparent to the casual observer. Having the owner's maintenance records handy makes this step a lot more fruitful. For example, knowing that the timing chain was just replaced instead of being 20,000 miles overdue for replacement will make a big difference in the value of the vehicle. Having a timing chain break can cause a lot of damage to a vehicle, and for low bluebook cars, you would probably be better off junking it and getting another one.
3) Check Edmunds for reviews and, more importantly, the bluebook value of the particular model of car you are going to purchase. You can select make, model, year, mileage and options. This is critical.
4) You might want to check consumer reports as well -- they have some good information on used cars (especially the lemons). You will have to subscribe though.
5) Check crash ratings from NHTSA and IIHS. IIHS is the more rigorous crash test, but NHTSA does WAY more models.
This is all the crap I did when I bought my last two cars and it's a real eye-opener on how many models are infamous for bad reliability, but only among their owners and mechanics. At the same time, there are some near bullet-proof designs that will last until rust finally consumes the poor beast. For example, old Toyotas' with the 22R engine (pre-fuel injection), Ford Crown Victoria's (2000's) and many Honda's have CRAZY reliability.
Most importantly -- have fun!
http://www.youtube.com/watch?v=pTaTitRENDM