I have the best luck when I stretch after a run instead of before. I believe it's better to stretch warm muscles, not cold ones.
There are good resources out there, the Run-Walk method that people above have described is a great place to start (Jeff Galloway sells a lot of books touting this method - try the library, as I didn't feel it was worth owning.) Basically, it gives your body a chance to recover from all the stress you are putting on your joints. I have bad ankles, so I focus on ankle strengthening (Stand on one foot and keep your balance.) I felt some knee and ankle soreness, but if it's not a sharp pain, I don't worry about it. If it's intense pain, I rest it.
It was also crucial for me to have good shoes - go to a running store, have them fit you with shoes and don't be afraid to run in them and really try them out. You could also look into a 5K training program like Couch to 5K and RunInspired. At the same running store where you buy your shoes, you could see if they have "fun runs" which are weekly groups you could run with once you get comfortable running a couple miles. Those have been really good for me, and I get a lot of great tips. It's also nice because you see all sorts of people, not just "runners" of the body type you picture in your head.
Take it slow. Three years ago, my major victory was that I ran a whole mile without stopping. Now I am training for my fourth half marathon, and love running. I think it's a cheap, efficient exercise that I can do just about anywhere. Find somewhere beautiful to run, and you'll be in heaven. ( I prefer running outside to the dreadmill.)
Good Luck!!