I think on gambling the most important thing is to control the emotion of a gambler and to do that the person must have to be able to self control, money management, decision maker (who can decide anything which s/he wants and the more important thing is that his control on gambling by not be too greedy and at the same time try not to recover at the time of loss.
Self control is just something else that we talk about almost all the time but not all gamblers take that very seriously as it appears hard for them to follow, I’m happy to see that in your last statement you said “don’t be too greedy” which show acknowledging that gamblers are always greedy in nature it’s just a matter of how much you can control that greed.