There is no safe method to gambling nor are there secrets to success in gambling. Gambling's its risks and luck.
Obviously there isnt, if there was such a method of strategy by which someone could make himself safe from losing anything in gambling then everyone would have been earning thousands of dollars everyday in gambling and no one would make casinos by spending so much capital on it, they invest because they know they will get a lot more then that in just a single day if the site gets attraction.
Then, the answer would be the investment, as a gambler since we cannot defeat the house due to house advantage so we should be wiser now. Invest in a gambling site and let the gamblers lose their money to profit your interest, I think that is the safest and the only way to win in gambling.