I think the best source of bitcoin is trading. After that it may be mining or one can earn bitcoin from bitcoin forums..
I think mining is not the best method again see that the longer the time ROI. may be more than 6 months now to ROI. in contrast to a few years ago. mining became the most favorite method because it is profitable and does not need a lot of time
Mining may not be profitable for every one due to many reasons. Electricity costs, setting up costs and then maintaining costs. With increasing difficulty and halving the enthusiasm for mining seems to have decreased these days, but then theoretically the difficulty should decrease if they leave pools but that never seems to happen so I guess is the other way around.
Be careful of cloud mining though - they are mostly scams and are made to steal your money.