Loiter around this site.
You'll soon get a good feel of what to look for and what goes wrong.
Personally I'd look for something with light mods. 2" lift, good mud tyres and maybe extractors.
Check for the usual mechanical stuff. Oil leaks, slop in drive line, strange gearbox/transfer noises. Select 4wd lock and unlock hubs. Maybe able to talk down price if they are not up to scratch but they are easy (read cheap) to fix.
