Most technqiues of gaining Bitcoin are a waste of time, such as Bitcoin faucets or Bitcoin signature campaigns.
You need to do something at scale.
I would say trading is the easiest way to gain (which in itself is a form of gambling).
Well in terms of speed trading is the best but be reminded that it may bring a potential risk than the two things you said earlier. While signature campaigns and faucet claiming only gives a little amount(or maybe a decent amount) of bitcoins, it is always at a low risk and had a low chance of having you lose your bitcoins because you are not staking any compared to trading.