This is a subjective thing and a lot of variables play into it.
Two to three times a week I think is a good running schedule. Depends on what distance, your age, physical condition, medical condition, and so forth. I'd stick to a treadmill on a 1% incline or rubber track surface (no incline obviously) if you want to really be careful about avoiding injury. I would NEVER advocate running on concrete or asphalt, good way to develop stress fracture and/or destroy your knees. If you run on dirt or grass (i.e. cross country terrain) be very careful about potholes, exposed roots, and loose soil/sand/mud. Oh, and don't be that guy that thinks he going to go from the Couch to running in a plate carrier or with a ruck on, that's just full retarded and a guarantee to destroy your body.
The C25K App is an excellent app for new runners or those who have not run in a long time to methodically work up to a 5K distance and they have a 10K program if you want to go over 5K eventually. This is a really great program, it will have you doing intervals up until around Week 7 (if I remember correctly). It's going to start you off with very short runs broken up with longer walks and steadily switches it up until your runs are longer than your walks and soon your runs are going for longer and longer steadily and at a realistic progression. There are times when you'll even feel like the program isn't pushing you hard enough, but follow it anyways and let it do its thing (trust in the program). You can listen to music while you run the App, and the App will break into your music to let you know when to walk or run, when you're half way through, and when you've got one minute left so you can sort of check out brain wise and just do what it says without having to check anything (provided you have some headphones).
Good shoes, good soles made for running and to absorb impact. Heart rate monitor watch or other smart device you can easily look at on your wrist is handy.
Listen to your body. Don't be some bull headed dude that sticks exactly to someone else's made for the masses schedule or program if your body is telling you to back off. If you start feeling knee discomfort or shin discomfort listen to your body and maybe you cut down to two runs a week or you slow your pace down so you're not pounding the shit out of your joints and bones. Everyone is different, nobody knows your body better than you.
I wouldn't run more than three times a week. Running is NOT the only cardio on earth. Spend other days doing low impact cardio that still gets your heart BMP up into the 130s steady (bike, rower, swim, etc.). Guys who are smart will run for years, guys who punish themselves like sadists are going to develop stress fractures, knee issues, and eventually they're going to have to give up running for long period of time and possibly will never run again. Steady consistency wins every time over some balls out program for long term health and happiness. Don't be David Goggins, don't put yourself through a simulated BUDS Hell Week, be smart.