I keep track a detailed excel sheet including accounting the brokage cost at enter and exit. I also discounting the opp. cost at a benchmark rate for the duration of holding period. One easier way is to keep track of your deposit transaction, calculate what you will get if you keep it in the bank. And compare the amount you have at your trading account. Also, you can record your daily NAV of your account, you can keep track of your growth easily. Just remember deposit and drawing should not change your growth rate calculation.