I've said this before, but it bears restating: if you are applying for NSF funds and have never been on a panel, you are shooting yourself in the foot. There's always questions about how panels work, but there's no substitute for doing it yourself. It is a TON of work, but worth every second.
So, how does one get on a panel? Well, it's a good idea to actively seek the opportunity out. You have a huge advantage if you have a semi-rare knowledge base or work in a state that isn't flooded with NSF PIs, but no matter what you should put your name out there. If you have submitted to a panel you obviously can't ask to be on it, BUT, the preproposal panels are already pretty much filling up, so if you don't get on one of those you could always ask to be on the full proposal panel, should your proposal get cut in the first round.
Regardless, you should contact several POs from different programs to put your name on their radar. It may take a bit to get called if your work, institution type and state are well represented, but you just have to keep trying. Ask, Ask and ask again.