Anything other than signature campaigns and gambling.
A bit saved is a bit earned. So save your money by not clicking on any of the signatures of the people posting in this thread.
Actually it would be easier to make business on bitcoin if you have enough capital. Gambling will be the fastest way but also the riskiest. Trading is the regular method with small risk to hold and really requires good estimations. Long term investment however would take the longest time but it is guaranteed to earn money with also some small risk