Although many in here advise signature campaigns, which are a legitimate way to earn your first BTC, the best way, in my opinion, is to sell a skill of yours. Personally, I write for people within the Bitcoin community. If you can draw, code, etc., then providing your skills to the community is much more helpful and time efficient for earning Bitcoin.
Agree to that, signature campaign is only good but not as much as earning from selling your skills as you can earn much better than posting here for few cents. Signature campaign should only be additional income and not relying to it as most people are doing