Shoot dark, yes our cameras like to expose "correctly" on automatic, but a correct exposure isn't just what a light meter says it is. We have to think and look at our screens. Are you taking a group photo? Are you taking a landscape photo, or a portrait? Whatever you see on your phone when you take that photo is filled with information. Is your background too bright? Is your subject too dark? Is it all just too bright? These are all things you need to keep in mind because the photo you eventually snap will have a certain amount of "working room" or Dynamic Range.
What is Dynamic Range? It's the ratio of the brightest to darkest intensity of an image that can be reproduced by a camera. This means that if you are taking a photo of your friend during sunset and the sun is behind your subject you will get more detail on your friend's shadowed face if you are shooting with a camera that has a high dynamic range compared to one that has a lower dynamic range--like our phones, all while preserving the detail of the beautiful sunset in the background.
To get better pictures from a low dynamic range camera like the ones mounted on our phones you have to be aware of exposure. Digital cameras in general are better at capturing detail in dark areas compared to very bright areas, which is quite opposite to "film" cameras that use film. Thus we should adjust our photo's exposure with the exposure bar. I will use this photo I took in Barcelona as an example:
Apart from the obvious move in framing you can tell the first photo is much brighter overall and has less detail in some of the brighter areas of the picture compared to the second picture. The horizon in the first picture is swallowed by the sunset while the ladder is maintained quite a bit more and has more detail in the shadows despite the brightness of the lights on the theme park and sun. To preserve the detail in the highlights or brightest parts of an image you need to utilize the brightness bar on your phone.
If your photo features highlights that are too bright and can't find detail you should lower the exposure bar so that the detail can be seen on your screen. The opposite can be applied to subjects that are too dark, however always keep an eye on your background as you don't want it to "blow out" or detail to be washed away by brightness. In general, however, it is always better to shoot darker than brighter because it is much more easy to fix in post production (on a digital camera)..but thats a topic for another time.