The expression "be careful what you wish for" applies to petitions, too. Your petition's "ask" is key to your ability to win -- the right ask defines victory, while the wrong ask can make it impossible. Here are a few simple tips to help you make the right demands for your petition.
Pick a solution
There are often many ways to solve the same problem. For example, you could combat a company's influence on a politician by passing a law limiting donations to candidates, getting candidates to voluntarily reject donations, or by asking corporations to stop giving. Make sure you consider different solutions for the problem you want to address and choose the best one -- generally the one you can win with the least work.
A good goal is clear, quantifiable, and concrete. If you don't spell out exactly what you want, it's easier for your target to pretend to give you what you want without doing so. It also means it's more difficult for you to know when you've won. If you're asking your town to adopt a living wage without specifying how much is necessary, you may not know whether the 10% increase they pass is sufficient to declare victory.
Make it winnable
Your ask should be something that can actually happen and that your target has the power to do. Changing state law is not something your principal can do, but she may have some discretion in how to carry it out.
Know the facts
You don't need to get into all of the details publicly, but it's good to know a bit about what you're asking for. For example, you could waste a bunch of effort asking for something that already exists but isn't enforced. Do other places do the same thing? Why hasn't your target done this without you asking? How do you expect your target to respond to your petition?