Originality
First and foremost, for your work to have copyright, it must be original. This means that the work is the result of your creative endeavours. It does not have to be new or even innovative. Creative merit is also not relevant: in other words, if it is a photograph, it does not have to be a good photograph; your poem does not have to be a prize-winner, and your song does not have to be a smash hit. As long as you invested skill, time and effort in creating the work, and did not copy it from anywhere, it will be considered original.
However, you cannot spend 12 hours carefully drawing a circle on a piece of paper and expect to have copyright.