I re_Started ours two years ago.
You start by talking to the principal. You feel them out for what a PTO could do for the school. You get their support for starting one. You get their help in using whatever communication vehicles they have at their disposal.
At the first meeting, we attempted to define our mission.
Some time well into our first year, we attempted to start working on bylaws once, but the year ended and we never got enough traction. We are not a 501 (c) 3, yet, but I am starting discussions about this with the school and school district to determine need.
We have a couple of teachers that are our "sponsors". We mainly do after school events, starting at 6pm so teachers and staff can get home at a reasonable hour, but working parents have time to get there after work to help volunteer.
We have one meeting a month and one event a month.
The events are what keep people coming back to the meetings. They are better attended by parents also. We have a plan at the beginning of the year for all the events. We usually spend most of our time at each meeting making sure we know what will happen at the next event, quite often talking one to two events ahead.
We don't charge dues, because we need the people more than the money, so the money can come in time. The sports also need money, so we don't focus on fundraising. Mom and Dad are hit up enough already.
Our biggest expense last year was also the teacher appreciation lunch. I took off a couple of hours from work and showed up to make sure the competely sub shop catered event went well.
At our events, we set up a table and sell pizza by the slice and canned drinks. Occassionally we also do candy bars and individual bags of chips.
The reason I set out on this endeavor is I saw the school had a weak reputation in the community. They had all these teams that has games, and as a parent (of a student that didn't participate in these) couldn't even find out about the games.
Let me encourage you to think heavily about what it will take to communicate effectively to the parents, without knowing who they are and how to reach them.
My way of reaching them was to show up whenever they were likely to be around and have a table to collect names, addresses, email addresses and phone numbers.
It can take a considerable amount of time, just organizing the information you receive, but it is essential.
Then you have to be self discipliined to communicate as frequently as you can afford to, without being overbearing. For me this means an email or two per month.
Last month, at a meeting, I brought up the cost of mailing to members that did not have email. It costs about $40/mailing to reach the 1/3 of our members without email. Since most never participated, they decided not to spend that money. I'm hopeful that will eventually be reversed.