All suggestions you mentioned are the way of getting free coins or tokens. But do you really think it is that easy? Do you think the value of those coins will actually rise extremely high? They are given away for free, so chances are that they won't. And bounty, airdrop and quiz/giveaways are actually not really worth it if you are a serious investor. They are just waste of time. You could do something more efficient to earn more using the same amount of time and concentration.