HI, look out and check for the following
rust!
arches,
rear inner arches pull the carpet back in the boot to check
sills
front cross member
sump
check heater blowers, if only working on number 4 then new reostat card is needed, about £30 from nissan
listen for a rattle from the engine, should be a rattle on start up for a few seconds, if it still rattles when warm then timing chain needs replacing
dancing rev counter, if fitted with a rev counter, if the needle is all over the show then more than likely new clocks needed
and just look over for the usealy things such as look for accident damage, tyre wear, etc, also recomend doing a HPI check
im sure others will add more