Always let someone know. Have you ever seen 127 hours? With James Franco? Right, well if you haven’t watch it. It’s great movie. But in short, it is based on a true story and a guy goes out hiking by himself. He doesn’t tell anyone and he gets his arm stuck in-between a boulder and a rock. No one comes for him because no one knows he is gone and has to cut off his own arm with a blunt knife to get free. It probably won’t be as dramatic for you but if you strain your ankle miles away from civilisation and you are not being able to get back, the dangers are very real. It can and does happen and if no one knows you are gone how can they call for help? Facebook, text, phone or email someone and let them know where you are going and when you will be back AND what they should do if you are not back by that time. That is absolutely crucial, no point just randomly messaging people, make sure they understand the severity of it if you don’t message them.
Here are two great videos on hiking safety and the essentials you need. I have no affiliation with Simply Hike. I actually think their stuff is overpriced but, the videos are very useful.