There isn't really alot to say as far as help goes. The only advise I can give is spend most of your time looking in the bulidings with a gun symbol on them, and Always keep the chainsaw in reserve just in case the zombies get too close.
like most people above me already sayd: use machine guns and keep the chainsaw as extra. what I would also say is: stay a long time in the first citys and go throug all buildings. and then you will have enough food to walk throug that big city (forgot the name sorry) without having to stay there more then one night. and don't use you mines and stuff in small citys (sorry if you think that's to obvious).