As stated in previous post, you'll not earn money directly with staking. Staking is like mining, without need to have expensive hw. As with mining you'll get additional coins which you stake. The difference from mining is that you actually need some (more the better) initial coins you would like to stake (some kind of "seed"). The % interest depending on coin, they can vary from 5% to 30%, that is for coins i stake. I believe there are coins that have bigger % out there.