I do not consider as source of bitcoins HYIPs, MLM Tables etc. From rest sources, mining not only bitcoins but other altcoins and exchange it is good if someone has money and time to invest. Trading is not for everyone; Need education, very good information, positive psychology and nerves made from steel. So for the rest of us others is my opinion, that is selling goods or providing services where others pay you with bitcoins.
Exactly, selling or providing something is better than others.
Mining is not profitable anymore unless you have cheap electricity and huge capital then go build your own mining farm, Trading either bitcoin trading or altcoin are risky it more like gambling if you dont have some criteria like sportis mentioned above, so far i don't recommend hyip, bitcoin doubler, MLM or something like that, also gambling if you win you just lose it again.