Moniker - generally I find people are interested in their children's school and education - as evidenced by the numbers that turn out to see school plays and the like. A very small number (maybe c.2 children in each year of 60) are from 'deprived' backgrounds - not just lack of money, if you know what I mean.
Some people (from different financial backgrounds) get offended or just find it extremely difficult if they are constantly asked for money - so keep a track of when and how often you make requests, and also ask school to keep you informed as to when parents are being asked for money for school trips and the like, so you don't coincide.
If you want to raise serious money, then make sure you tap any business contacts within the parents for sponsorship of events or raffle prizes or straightforward donations.
But PTA doesn't have to be about raising money ... school can benefit a lot by having parents willing to come in and listen to readers, help in a craft class or sewing, or a chess club, organise a book sale or running an occasional disco. All these things can be (but don't have to be) organised through the PTA. Even an annual fair can be more about everybody having fun than about raising money. Make sure that everyone who volunteers their time is well-briefed/trained as to what they are going to do, and make sure they are thanked and feel appreciated.
With regard to the actual PTA meetings - make sure they are run efficiently. e.g. (unlike ours) they start and finish on time, dates of future meetings are fixed in advance and stuck too, and that meetings are well-chaired with all opinions listened to and if appropriate acted upon.
Good luck - hope it goes well for you!