I stumbled across this website when I was looking for tips on how to improve dialogue between characters. There are other great writing technique tips on this site as well, it's worth a look. http://www.novel-writing-help.com/writing-dialogue.html
Sally and I both went to this talk at Abingdon Library a couple of weeks ago. It was presented by Ilaria Marconi of Hersilla Press but don't bother to rush to check out the website unless you're an Italian crime writer!
To be honest, she didn't say anything we don't already know but I'd say these were the key points:
Write the whole book before you start sending out submissions.
Research agents and publishers carefully - read their submission guidelines and adhere to them. Ensure you are targetting agenst/publishers who specialise in your genre.
Know your readership and illustrate this in your submission letter.
Keep the query letter short and concise.
Show you have researched your market - the competition, who your writing is similar to, etc.
Include any ideas you have for publicity and promotion but be practical and sensible.
Have you been published? Tell them!
Above all, be professional.
She also gave a handout of useful websites (thanks to Sally for these!):
www.bookendslitagency.blogspot.com - for examples of successful query letters
www.virtualsalt.com/rhetoric.htm - for examples of rhetorical devices
There was quite a lot of talk about self publishing as one of the audience members had experience in this area, particularly in e-books I think.
I haven't had time to check out all the websites she recommended but I think this was probably the most useful bit!