It works mostly within the system and helps parents hold schools to high standards. Other local groups focus on tax reform, school choice, special education, etc. Some parents, such as Richard Innes of Kentucky, become experts in one area. His watch-dogging has led to major changes. It's not easy to get them, but it can be done.
Most districts have a multi-year improvement plan, as well as summary and detailed budgets.
Read original documents whenever possible, instead of press releases. Vigilant, assertive parents may take a lot of heat when they buck the status quo. Administrators, even school boards, may put you on the defensive, make you look foolish or uninformed. Be prepared for diversionary tactics. Learn from others who do their homework and present arguments so they're heard.