Putting bet base on critics/analyst/prediction sites and mostly your own prediction is the safest methods to gamble. You can compare the upcoming match in advance and prepare some meticulous study about the teams .
Trusting other people's opinion is not safe either. Even the best people and professionals are having hard time to predict some games and even them they can't trust their own thoughts and opinion. That's it, that is the right thing that you can do to gamble safely. By comparing and researching about the matches or teams that will be involved or you will bet.
That's true, it is always depend on you!
once you are not sure of what you are doing or in your idea then it will really ruin your game and even your money will lose. Just make your own method, but for me, i suggest that always put in our mind that just play the amount that you can afford to lose. That's it!