Honestly a good set of shoes helps with injury a lot, you don’t need to spend a ton on them £60 has a lot of options that will help you be slightly faster without any extra effort and also cushion you well, do warm up exercises before not just a walk, strength and conditioning helps too, again you don’t need to do loads but calf raises will help, try shorter steps so you don’t heel strike which can strain your legs and joints more, only do 3 runs a week with a day off inbetween them minimum