I guess the best way to play smart in gambling is set a limit on how much loss you can take and a goal on how much profit you can earn. Its the same thing with trading, your number 1 enemy in gambling is your emotion. Some gamblers don't know when enough is enough. Bringing someone with you when you play is a good idea to remind you if you reached your limit.
If we set limit, we dont have to worry about losing alot of money especially money that we shouldnt be using. Alot of people think that there is no use to set limit but for me it is very useful. By setting some limit, it means we are playing smartly already. We dont play to win but we play for fun and if we win then that is a good bonus for us