One of the best places to find gems and do trading without too much volatility is Cryptopia.
In my opinion Bismuth is gem, cause it's not yet on other exchanges, and it's pretty stable and easy to trade.
So best tactics would be to trade gems like that, accumulate more, it get's listed on other exchanges and you earn big.

Disclaimer: I'm not associated with Bismuth's or Cryptopia teams but hold their coins. This is not financial advice, just my personal opinion.