what lot volume will be better for you completely depends on your capital. if you have bigger investment then you will be able to consider bigger lot volume. let you have $1000 in your account, then it will be better for you not to consider lot volume more than 1.5, where 1.5 lot= $1.5. it is the money management that i follow. be sticky to your MM, a good money mangement is the key to success in forex.