So you want to at least try to attract an agent and publishing house before you resort to self publishing your book? There is no guarantee that your query will attract the attention of an agent - but there are definitely missteps that will quickly rule it out! Sometimes it seems the list of Don'ts is longer than the Do's:

Don't call a prospective agent.
Don't send snail mail.
Don't email agents without first researching whether they handle your genre. (i.e. Non-Fiction, Fiction, Inspiration, Romance, etc.).
Don't say the wrong things in your query letter. (There is a list, trust me. Identify it. Obey it.)
Don't send to more than one prospective agent at a time.
Do send to more than one prospective agent at a time.

OK, do send to more than one prospective agent if you want and the website says it's OK, but be sure to let each agent know if you do. I know, I know. It can be confusing. All you want to do is share your life's masterpiece and now you have yet one more maze to navigate. They say "Life is a journey" for a reason!

The first step is to relax. Breathe. This, too, can be exciting.

Just think! Somewhere out there may be the person who is perfectly positioned to not just believe in your story, but help move it through that next critical step toward publishing.

Your goal is to find your new best friend.

There are several excellent agent websites that can help steer you toward competently navigating the labyrinth. Some are definitely better than others. Ask around. Find the agents who cater to your genre. Read them. Follow the best on Twitter and devour what they have to say. Take their advice. Comment on their blogs and make them notice you for all the right reasons.

Do all this BEFORE you submit your query letter.

It sounds like work and so be it.

Do be a "Do" bee. Don't be a "Don't" bee.

(OK, sorry. Just channeled Mr. Rogers for a second there. That guy was a genius.)

Do be positive, enthusiastic and confident about your material (if you've done your homework and your manuscript is well written).

Don't be frightened, brash or disregard the guidelines.

There are, of course, seasoned book mentors who can, for a fee, lead you by the hand through the fog and help steer you toward the right professionals. You can find them by word-of-mouth referrals or online research. There are no guarantees of success, because no one knows for sure what manuscript will ultimately strike a chord with a particular agent. But it can absolutely help to work with someone well versed in specific agent wish lists.

By the same token, if you have the time and energy, you can educate yourself and work your way to the right agent for you. Indeed, educate yourself, either way. Then, when an agent says "Yes, I will represent you," you will know enough to evaluate their level of competence and ability to represent you fairly and well.

You have your homework. Get busy!