Mining is a good thing to do here to get vitcoin. But if want to get bitcoin with out investing or capital, then you can try in joining the bounty campaign. It just need an effort for you to be accepted.
mining will need some money to buy the hardware and today, the hardware is too expensive because many people are trying to start mining. there are two ways that I know to get bitcoin which is by freeway or by buying bitcoin. and if you don't have any money, then you can start with freeway and you can try what suggested by another member here. and if you have money, you can directly buy in localbitcoin because you can find a good of sellers that will near at your home so you don't have to be worried about getting scam. and after you have bitcoin, it depends on you, what you want to do with your bitcoin.