Inorder to earn Bitcoin without investment you have to join various signature campaigns where you will be paid for your posts.As you are a newbie so inorder to join these campaigns you first have to increase your rank because very few campaigns are there for a newbie .When you will become a junior member you will start getting campaigns but your pay will be quiet low.The more you will post ,the higher your rank will be. The higher your rank will be ,the more you will earn .But for this you need to have some patience as it is a slow process but the results are guaranteed. You can then invest some part of your earnings in order to get more profits