Well done! We had our AGM last night and there were 6 of us: 4 committee members, 1 teacher and the (new) head. Of the 4 committee members present , 3 are resigning from the committee. As the 3 of us resigning were last year's chair, secretary and treasurer, we have something of a crisis! There are 2 other committee members who were unable to attend, but new blood definitely needed!
Suggest that you don't get yourself talked into doing anything you don't want to, though realise that is easier said than done. When I first joined a PTA committee 10 years ago I went in full of ideas about what could be done - not realising that they would probably already have a fair idea of what they were going to do. Exisiting committee members will have a good idea of what works well for the particular school, and what doesn't, so if you have a suggestion about an event, then don't be surprised/hurt (as I was) if it is not taken up. My attitude initially was to go to meetings, listen and figure out what I could do. I would offer my services for things I could do, then could happily turn down things I would find harder.
Eg one year offered to take on job of writing to local companies/attractions to request raffle prizes for summer fete. A dull boring task, but useful, and something that can be done from home. More recently I have been chair, just for a year. I have found that hard, I am not an "organiser", but often had to put in a huge amount of effort, due to lack of help from others, to make events happen. (hence stepping down from it now)
Above all, enjoy it, use it as an opportunity to find out more about how the school works, meet other parents etc.
I have really enjoyed my times on different PTA committees, but realise others have not been so lucky (there was a huge long thread about this earlier this summer).