Hi Paul,
Here's some ideas:
This site has the facility for a dedicated Plymouth page, like the ones for other areas, so we could get a web presence going very quickly. It's very straight forward to input articles & photos etc. and anyone doing a search for, say, 'Plymouth Humanists' would find it. This is South Devon's:
http://sth.devonhumanists.org.uk/Having an email list of local people who would comment on relevant media coverage is a good way to raise our profile. If anyone sees an article in the Herald or on the radio, for example, they email others suggesting they comment or write in.
Putting out Press Releases also gets the message out. Our Christmas Message was a success in saying that anyone - and not just Christians - could celebrate at this time of the year. The media sometimes just don't know who to contact for comments on some stories, so they just phone up the local Bishop.
It's also worth getting a representation at Plymouth's Equality & Diversity & Inter Faith & Belief Forums to msake sure that non-religious folk don't get forgotten when policies are being drawn up,
See you on the 22nd!
Kevin