This is just the basics, but anyone should be aware of it:
Budget: set it BEFORE you start gambling and stick to it.
Have a break from time to time, it is important to let your brain stop and consider.
Avoid drugs / drink as much as possible, they will make you loose some control innevitably.
Seek help if you feel you are no longer in control. Make a phone call to a friend or go out and speak with someone.
Anything else anyone can think of? Like... read this post before gambling?

Don't allow yourself get to the point of addiction because it is when you get addicted you then start to put up habits as drinking and others probably to help you was off the pains off your losses which on the long run you never get to forget those losses by drinking or drugs.
Most times these guidelines help to gamble responsibly but it's sad that most persons fail to be disciplined enough to want to keep to these guidelines which would have helped them become better persons regardless of their gambling habits, discipline is one key factor they should be considered because you could have a strategy and plans as well but if you are not disciplined you will still fail at it.