It’s a little bit tricky to find a job that will pay you in Bitcoin instead of your local currency nowadays, but they do exist, and if you can find one, this is a great way of getting Bitcoin because it’s so reliable.
You can even try asking your current employer if they will pay you in Bitcoin instead of fiat currency, even though they will most likely say no. You should consider asking even if you expect them to say “no” so that your employer knows that there are people who work for them who will accept Bitcoin. Small businesses may be more likely to accommodate this request than large ones.
If you have relevant skills, you may also consider freelancing using various websites where people list projects they need completed and how much they are willing to pay for people to complete them.
If you are a programmer, Bountysource is a good website for earning Bitcoin. You can implement features or fix bugs in exchange for a bounty that can be added to by anyone. Best of all, it can pay you directly in Bitcoin (or even other cryptocurrencies for certain bounties).
You can also look at communities like the Jobs4Bitcoin subreddit.
You should always make sure that you agree on terms through a contract before you take a job. Otherwise, there may be miscommunication about what is expected from the other person. It may also be a good idea to ask for payment in multiple instalments instead of receiving it all at once to lessen the risk.