In cases of trading , campaigns, gambling and mining, I Personally trading. Because Gambling isn't a form of earning. If you gamble long enough, you're going to lose everything you wagered. Casinos, online or in real life, don't exist to make you rich. Mining is a very big process, need huge procedure to implement. But investing or trading is good and I like personally.
Apart from gambling the rest three are good for making money. If you have no money then you can make money in campaigns for free. If you have trading experience, you can make huge profits from trading. If you have no trading experience and can mine crypto then you should start mining today, but also needs skills and knowledge to use your time well.