The best way to earn crypto currency is by changing your habit. Stop looking for "easy" ways to earn money/crypto currencies. Offer your service. Show what skills you have and what you are able to do. Sell your skills. Look through the forums to find such jobs or create your own thread stating your services you can give.
What service do you offer? I couldn't find any.
Let's start with airdrop. Airdrop is like a promise that participants will get reward if they complete some easy tasks, or give away some information. It's free and easy to do airdrop. Participants need to wait for the project to be success in crowd sale first. But sometime any old coins can give airdrop too. Airdrop is good to try for newbies who are new in cryptocurrency. So they can learn about how things work without risk of losing money. People who're new to this forum and don't have money to invest can start with airdrop first. Airdrop's reward might seem not attractive for most people. But you can gain lot of reward if you refer many people to join. I know someone who's managing his own telegram group just for doing airdrop. He earned lot of money by refer group members.
How much money his referrals have earned?
Next is bounty. Bounty is like a promise that bounty hunters will get reward if they complete some tasks. Sometime these tasks are difficult and they have to compete with each others to get more share. It can be tough, tedious and time consuming. Bounty hunters also need to wait for the project to be success in crowd sale first. Bounty is great for people who has influence on social media. Any talents content creators and old time members on this forum gain more advantage from bounty. The higher rank you are, the more reward you can expect from. And it's free to join too. Bounty rewards are more attractive than airdrop. If you find a really good project to do bounty for, you can hit a jackpot and make lot of money.
I agree that bounty is great way to earn some money, especially if you hit one of those high paying bounties but I disagree that it is time consuming to post few posts.
Now is long term investment. This choice is good for people who have some money to spare. And they have to be ready to spend some time to study about the project they're gonna invest. You can make lot of money if you can find and invest in promising projects at low price. Gaining 10x, 100x or even 1,000x is normal in cryptocurrency market.
If you found such project. Most projects won't give you high returns and in most projects you will lose money. ICO is high risk investment.
The last choice is trading. I think this is the worst way to earn money for most people. Trading is only good for market makers or very rich people. If you have load of money, you can craft a very beautiful graph and lure traders to buy your bag. Let them believe they're buying a coin which gonna get pump soon. Then walk away with their money and never look back.
I disagree, trading is one of the best way to earn money, you only have to read market and follow some basic rules.