I'm new just like you, but I've picked up a couple of tips. First, check out the Wiki. There are some guides there (
http://wiki.urbandead.com/index.php/Guides) with some helpful noob tips.
Also on the Wiki is a set of maps for the different suburbs (
http://wiki.urbandead.com/index.php/Suburb). Some suburbs will have a list of which buildings are barricaded and by how much. A lot of the communities have barricade plans to make things easier for survivors where strategic buildings are built up just enough to keep zombies out, but not people.
First aid kits are (so far as I know) the common way to heal up. You can find them in malls and hospitals, but those are either barricaded too high for starting out characters or are infested with zombies. What I've been doing is laying low, taking a few potshots at zombies and reading books to increase XP. I'm saving up for the Freerunning skill so I can get into a mall and scavenge some first aid kits and decent weapons.
So far, other players have been really generous with their heals and revives, which is great, because without a little help from our friends, being a newbie civilian survivor is pretty tough....Good luck.