I was also heavy when I started running so I can give a few tips.
- Things are going to hurt but if its sore on both sides its fine and just needs some rest if its on one side you need to take a break/physio.
- You are going to have to try a few shoes to find the perfect one and this is going to cost.
- Get on the road and do your runs it so much more fun.
- Don't be afraid to walk run walk run to do a 5km, the object of many runs is getting used to being on your feet.
- At some point you are going to need a watch, personally Garmins training programs are great and I wish I had followed one when I started. A secondhand Garmin 45 goes for around R2000 and is a great watch.
- Don't run flat out everyday (once a week max) or you are going to end up injured. Find your easy pace and stay with it, you will naturally get faster and when you do your fast run you will see the difference.
- Make sure you are having fun with running and do at least one fun run a week where nothing matters.
- Once you are ready find a club, group or bunch of runners. I have three different groups Tuesday are braai and beer in a parking lot after a 6-10km run, Wednesday is a club run 5-8km run, Thursday is my own fun run, Saturday is the trail friends and Sunday is the long run club runs. Having all the different groups/friends keeps you motivated and you start getting messages at 11pm for the next day "30km cradle run tomorrow" or "heading to kliprivers for a 20km for anyone interested".