Before buying always check the coin wallets on both exchanges to see whether deposits or withdraws are disabled. Also generate deposit addresses on all coins beforehand.
Note: All prices are in USD, some exchanges only show prices in Bitcoin. Also the price difference of altcoins are shown versus the price of Bitcoin on its exchange. For example if a coins price is exactly 0.001 BTC on 2 different exchanges yet it shows a 3% price difference it's because the value of Bitcoin has a 3% difference on the exchanges. So if you were to transfer that coin and sell it to BTC you'd make a 3% profit (minus order fees).
BITCOIN GOLD (BTG-USD) bittrex - 0.0000000000 Buy on bittrex and sell on bittrex for 0% profit
PERCENTAGE INCREASE CALCULATOR
Don't transfer MAID BTC (slow, high fees)
Don't transfer Ripple (XRP) or Stellar (XLM) to poloniex. Repeated history of coins transferring slow due to poloniex hot wallet delay.
Pro Tip: If bitcoin has a 3%+ price difference on exchanges it's not recommended to take that risk with arbitrage because bitcoin transaction fees are high and if the network is congested transfers can take hours. Instead you could buy the btc version of another coin (like XRP-BTC) and transfer it fast and cheap. Next sell your XRP (or whatever coin) for BTC on the higher exchange, and finally sell your BTC at the profit difference (minus order fees).
Tip: Typically you'll see a pattern of the same exchanges having prices lower than others, this is due to lower volume and cheaper fees. Taking advantage of a great opportunity is buying a coin on the cheaper exchange when it hits the support level on the higher exchange. For example, if Binance prices are always lower than GDAX, then when a coin on GDAX hits a support, make your buy entry on Binance. Based on probability, even if the support is broken by the time you transfer to GDAX you will still be in profit range.