I could call those lucky to do arbitrage trading because it is not easy to get the coin while we need to send it to the other exchange and sell it at the right time. You can not just buy the coin at a low price and hope to profit from the other exchange because you need to think about how long the transaction will complete the confirmation. I suggest you trade in one exchange, focus on one coin, and make a profit. If you can do that, you can try with the other coin but not use arbitrage trading because you need more experience and skills to determine the coin.