Best source of bitcoin used to be signature campaigns here, but the payout these days is very less as compared to old days.
Now the best source of bitcoin is trading and investing them or maybe giving a collateral loan to someone.
I agree with that, signature campaign is really one of mg favorite way to earn bitcoin, next to trading. Though I do not really like making some collateral loan because sometimes they make a run from the one who made the deal or the one gave the loan, but that is really rare because we are using escrows to witness the loan. I did invest my money on bitcoin, but I dont think I can invest on something like gambling sites, trading is a good choice too but we must learn a lot of things before taking on trading because trading, also has a lot of risks.