In the UK, it is very easy to get involved with surveying birds through the British Trust for Ornithology.
They run a number of different kinds of survey throughout the year, each with a different methodology.
This is a run-through of the Breeding Bird Survey process, and a fairly blatant request for other readers to get involved. A lot of the information and methodology comes from the BTO/BBS website, but modified from my own experiences.
(I will be assuming that you are already a birder of some level)
(There are some small edits for the 2011 season, mainly minor changes to websites.)
Step 1: What is it?
It is a nation-wide survey, designed to be simple to take part in, aimed at keeping track of the wild bird population of the United Kingdom.
The data is used to provide both national and regional trends for bird populations.
The status of wild bird populations is an important indicator of the health of the countryside, and has received much greater interest from the Government and wider public in recent years. ... BBS results are being increasingly used to set conservation priorities by Governments and non-Governmental organisations.