one of the most profitable ways is altcoins trading. although it is so risky but it is possible to double your btc in one trade only and in few hours. but you have first to choose a trustworthy exchange which has great reputation.
But I do not recommend alt coin trading to get more bitcoins quickly. Because it is highly risk same as bitcoin trading. Alt coins are highly vulnerable to dump at any time in my experience.
So, buying any alt coin must be getting your bitcoins into high risk.
Since this topic is aimed at newcomers altcoin tradiing is not recommended.
I for one would advice to start with faucets and start learning bitcoin.
I think altcoin trading well enough to earn a quick profit, but you have to really understand all about trade altcoin, otherwise you will always lose.
faucet just a waste time to get a few cents/hour, not a good suggestion.