Calatheas, and their close relative Marantas, like their soil to stay moist. They love humidity and struggle if underwatered, often developing brown tips on their leaves. If your plant is happy and healthy but still has brown tips, consider switching to distilled water, or water left to sit out overnight to help eliminate some of the chlorine and fluoride since these plants can be a little finicky about their drinking water.
These plants like lots of bright indirect light (think 2-3 feet from a sunny window.) Too much direct sun can cause burns on the leaves so if you notice any leaf browning in the center of your plant's leaves, move it a little farther from the light. It's also a good idea to rotate your plant every once in awhile as Calatheas and Marantas are notorious for growing toward the light. Rotating will help keep your plant's growth even.
These plants are notoriously finicky but it's easy to forgive them because they're so beautiful. We like to say that they're easy to keep alive, but hard to keep looking their best. So don't be afraid to try new things, move your plant to different locations to find the one where it's happiest!
Calatheas and Marantas are non-toxic, so no worries!