at what rank should i start? im rank 170 and i probs will after i get kronyn

NOW, you should have started a long time ago!!!!! also kronyn is not a good race to NPC, human, ineregon, and drannik are races you should NPC with

Hi Destroyer..I can understanding hunting for uncommon and rare NPC..however, is it worth huntng also the common ones?

for the experience, yes on MOST common ones, the stryll assassins (and maybe tech collectors if you don't have the attack and defense) are a pain to go through at lower to mid ranks and therefore don't give a good experience ratio.