Pick up Botany or Miner (my guess would miner would probably find them sooner than botany) and just go and gather fire shards. I spent like 30 minutes and had gathered around 150-200 shards once. This also helps all your crafts when you need shards (or any material for that matter, you will save a fortune on iron ore if you go mine it yourself) Plus shards are generally low level so you don't have to raise the gathering class to high just enough to start gathering the shards you need. :3 Hope that helps :3