The thing is first to master the ability to control your greed, because that's the most important of all . Many gamblers have tried to control their urges but to no avail and which deals to them going off from all the plans they have installed ahead of controlling their habits. In gambling discipline is all and that's what most humans in general don't have and if you look carefully most of these are gamblers and this habit contribute to all ill behavior relating to gambling.
There's a saying that everyone have greed in them but not every that have the ability to control their greed. In regards to what OP already said, anyone that wants to gamble or spend their hard earned money on gambling, the person should first consider if they can afford to handle the negative outcome of their bet. Some people are just being swallowed by their greed that they don't even think about the consequences of staking on a game with a very high amount. It's after they have encountered a huge lose, that's when they start to blame themselves.