here are some of my favorite tips:
first, get to know the words "unagented" and "unsolicited." unagented means was not submitted by an agent. unsolicited means that no one at the publishing house asked for the submission. If you are in a position where you can not afford, or simply do not wish to hire an agent, you will lean to soliciting. contact the publishing houses of your choice, (i would suggest picking up a copy of 2002-2003 writer's guide to book publishers and literary agents, by Jeff Herman) if you can get them interested in what you have to offer, they may ask you to send all, or part of your manuscript.
Try getting published in a magazine or newspaper first. Being able to write in your query letter that you are a published author will give you a boost.
how to stay out of the slush piles:if you submit to nobody, then nobody will recieve what you submit.
get the names of the editors that are prominent in your field. you can call up a publishing company and ask (for example) "who edits your fantasy novels?"
contact by sending a letter describing your book, (or a query letter.)
and do not send full manuscripts unless you are invited to do so.
A TIP OR TWO ON WRITING ITSELF:
never stop writing for the day after you have completed a scene. It will make it harder to get back into the flow of your book the next time you begin.
try to write every day, even if it is only a paragraph or a few sentences.
watch and listen to the things around you, as they say, life immitates art.
there is so much wisdom about getting published out there that I could go on for hours, but I will spare all of you.....