your local party who gets them from the County Recorder.
If you are just trying to get a feel for your neighborhood, you can do a "voter survey" and just ask folks what is the most important issue to them in upcoming election. give them 4-6 choices and see what you get.
be sure to have materials with you to help them keep in contact with you. I set up a special email address (from one of the 10 my ISP provided me) for party stuff. Ask folks if they want email updates or give them your email. also if there is a local candidate you are trying to help, have their materials too.
or do a "partisan walk". Ask the folks who are already Democrats (as listed on your precinct list) if they'd care to help you (get more volunteers for your precinct) and see what kind of time they have available and what they'd be interested in doing.
or you can do a registration walk. check your precinct list for addresses where there is no (or only one) voter listed and then see if you can get some new people to register
NEVER leave anything in mailboxes EVER! it's illegal and not worth the possible problems, but a rubberband will hold most anything on a doorknob
you don't need a "party" person to go with you, just take your kid or a pal along. safety is the issue always go in teams for your safety!
always have water, voter registration cards and pens with you. you'll need them all
in 2004, I had a Kerry bumpersticker on the back of my clipboard and I always dress in REALLY patriotic clothes LOL
good luck and let us know how it goes
