Put your idea down on paper. Develop a pitch or outline of your pilot episode. This way, you have something down on paper that you can protect. Get advice from friends and colleagues to sharpen your idea.
Register the outline with the Writer's Guild of America. You may register at Writer's Guild West or Writer's Guild East, depending on where you live. You may register online, in person at a Writer's Guild Office, or by mail. For Writer's Guild West, the registration fee is $20 for a nonmember; for East, $17 for students and $22 for nonmembers.
Get a copyright from the U.S. Copyright Office. You can obtain one online (www.copyright.gov), under "Performing Arts Works." Registering a copyright on a script or outline is usually $45. Copyrighting is not a necessary measure, especially if you already have the outline and/or pitch WGA-registered, but it provides extra armor for your work.
Know your connections. You may have heard about nepotism in the entertainment industry and what you've heard is true: industry contacts are the key to breaking in. If you have respected contacts that also respect you, have them write a letter of recommendation to the right people and have your work read.
Get a job in the entertainment industry, especially if you have no contacts. If you do not have any experience in the entertainment business, start at a temp agency specializing in entertainment clients. Start with low-end work, whether as a receptionist or production assistant, and work your way up. Mention to your superiors that you ultimately wish to be a TV writer, but you will do whatever it takes -- even thankless chores -- to get there. Work hard and get the respect of your superiors, and they may be willing to read your work.
Submit your work to screenwriting contests. You will likely not get a job immediately after placing in such contests, yet getting placed looks great on a resume. Also, you will have industry professionals looking at your work who may give you feedback. You will often have to pay a fee to enter, a standard practice for legitimate screenplay contests.