You need to have live conversion of prices from the exchange you're buying from and the exchange you're selling to in the (two coins you're using) selling price of BTS/ buying price of LTC ... buying price of LTC/selling price of BTS

and you need to make sure the volume is enough for your trade. I'm not sure if Bitshare is on bitstamp. You could try binance, openledger, and poloniex using LTC, BTS or other coins. Just be careful that many people have arbitrage bots setup and it's hard to compete with them.

The STEEM internal market is not filled with bots yet, so it has a better chance for arbitrage