Yikes, this is almost as hard as writing the book was. I'm a first time writer, my book Pushing Up Daisies (St Martins 2008) is a funny (as in Carl Hiassen funny, she says modestly) mystery set in the suburbs. It's the first in a series with garden themes.
Gardeners have to be patient so I was well prepared for the publishing process. The writing took about 18 months, the publishing - going on 3 years. Finding an agent was the biggest hurdle. Advice to fledgling writers - don't give up. There are a zillion agents out there and if the first 5 or 50 don't like your book f&*k 'em, maybe the next one will.