Usually when I come into a system I scan the star, refuel, then scan for planets, but what should I really be scanning? Is it worth scanning the star? Is it worth scanning the every planet?
Dommarra's method of scoop honking until you hit something interesting probably has the best return/time ratio. That said literally almost every other activity in Elite pays considerably more than exploring.
You dont have to go 10 Kylie for lots of NS. Go +/-2000z in most arms and there are plenty, normally only about 2 jumps apart.
Having said that NS farming is dull, and hardly counts as exploring. As a cash generator on your way to somewhere else, OK. As an end in itself ? Might as well be trading.