Over the past 122 years the RSPB has been protecting birds, originally from the feather trade but increasingly also habitat destruction, climate change, over-hunting, and many other causes. Consequently, the RSPB's mission has been continually expanding without ever losing sight of their original formation rationale. The RSPB now have more than 13,000 volunteers and over 1,300 employees who work towards their goals and exemplify how you can successfully coordinate large disparate groups into a cohesive, functional unit which can accomplish many different conservation projects. The RSPB no longer only advocates (although it is certainly still their major focus), but also protect endangered species habitat. The RSPB is very extensive, and their various foci are varied indeed.
The RSPB understands the only way conservation projects will be successful is if you incorporate local people- this is the key. The RSPB educate farmers regarding ways which they can make their farms more wildlife-friendly and persuade the government to provide farmers incentives if they become wildlife-friendly, and have had great success through that endeavor.
The RSPB also reintroduces birds back into their former habitats after threats have been reduced, including Steller's sea eagles Haliaeetus albicilla, common cranes Grus grus, and cirl buntings Emberiza cirlus.
Just because the RSPB is much larger and better established than other conservation organizations I cover is not me suggesting the RSPB doesn't also need help. They do incredible work, their money is well spent, and their results are astonishing. The RSPB needs assistance, from monetary donations and goods through volunteers. If you enjoy wildlife and live within the UK (or possibly outside the UK), I can hardly imagine a better way to get involved than volunteering with this fantastic organization. Do help them if you are able so they can continue their amazing work.