One new addition for everyone, that a lot of people overlook.
The best way for you to earn bitcoin is for you to do whatever it is you're most skilled to do (what's your job? your career?) and arranged to either get paid for that work directly in bitcoin or take the fiat you earn and buy bitcoin.
When it comes to the best ways to earn money, you need to evaluate what skill you have that pays you the most money per hour. Focus on that so that you can get better and earn a higher rate per hour! It's easy to buy bitcoin, so don't focus on side jobs that pay dust if you can spend that same time doing what you do best and getting paid loads.
And if you want your employer to take money out of your paycheck to have it directly sent to your bitcoin wallet you should check out BitWage (https://www.bitwage.com/). But know that BitWage's fees are greater than if you just bought bitcoin on your own through an exchange.