Once you have a completed project, you can start submitting your work to agents and editors. There are many things to keep in mind when submitting your book or novella. Having a handle on all this will improve your chances of having your full manuscript accepted.
1. Read all guidelines for the publishing house or agency for their specific rules. They vary from house to house, as well as editors within a publishing house. Therefore, it is imperative that you learn what each editor/agent is looking for in a submission.
2. Abide by all guidelines. It isn't enough to read them. You must obey them, even though you think you should be an exception to the rule for whatever reason. Breaking even one rule, such as "Do not ask for a signature on delivery" will make a poor first impression on an agent or editor. So if you want this, or subsequent projects requested, do as they ask. You may not get a second chance.
3. Call the agency or publishing house before submitting any work to verify the editor's/agent's name, name of the publishing house/agency, their title, and whether or not they are still employed by the house or agency. Depending on the agency/house, your work may be returned to you unread if the agent/editor is no longer there. They have such a large quantitiy of submissions, they don't always want to take the time to re-route projects to other editors/agents.