I don't pretend to be an expert I'm learning too, but I have a few tips that I've learnt along the way.
 
You don't need a licence to hold a petition signing, just permission from the land owner.
 
Your email address book is a useful tool, contact anyone you know, and ask them to pass it on.
 
The same with sites like facebook, and twitter, get the message out there. Social networking sites can be linked together, this means if you post on one you belong to, and hit all of them at once.
 
Keep posting what you intend to do on here too, the more hits here, the more prominent we are on search engines.
 
Use the local media, if you are organising an event tell them, you may get them to come along. If there is a local celebrity in your area, especially if they have an interest in this issue, contact them. Its sometimes possible to reach them even if you have limited contact information.
 
Contact organisations that can help you, finding ones who are against Green Paper is a really good idea, but you can try getting your campaign noticed by the 'doubters' too.
 
MPs and councilors want your votes, they may be willing to support local campaigns if they think it will get them noticed.