Private investigators walk that fine line between adventurous and creepy. It's very similar to the line clowns walk. You can be the hero that saves a marriage or solves a crime, or you can be the pervert getting his car searched by the police.

If you ever thought you would be good at hiding and lying, then you might be able to handle PI work. However, a word of caution: You can never undo being a PI. It's like when you sleep with some nationalities, you can't go back. If you're still interested or simply want to know how to spy and not get caught, I've provided a few tips.

Check Yourself
To successfully follow a person, a PI should get familiar with the area. Usually any map Web site will allow you to locate the egress routes and the direction your subject will most likely travel. Since you've already paid $9 at the local Department of Motor Vehicles for their driver's license picture, vehicle and license plate (I'll explain how you do that later), you can now park your vehicle in the least conspicuous location to wait for your subject to leave their home. Parking in front of a playground is not advised. People will come knocking on your window to ask if you need help, but it's really just to get a description of the pedophile for the police.

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Follow That Car
Once the subject leaves, if possible, you want to keep a vehicle between you two. People tend to notice the vehicle behind them, but not the vehicle two vehicles back. Once you get good at this, you can start practicing driving ahead of the subject and anticipating where they are going. A little tip: Music can be a real inspiration when following people. I love listening to Wham!'s "Careless Whisper."

Get the Evidence
During this surveillance, you should have been collecting evidence via videotape. Now you can upload it to your computer, put it on a DVD and send it to the client. If you're spying for other reasons (aka stalking), you can review the tapes and sit there on your futon crying, because you now have hard evidence that your ex is dating someone better-looking than you and with a real job.

Be a Creep
When the subject has landed, the on-foot surveillance starts. As a PI you must always stay focused on what you are trying to discover, because the longer you follow a subject the higher the risk that the subject will discover you're following her. A change of clothes is a good thing to have. If the subject is going into the Piggly Wiggly, she is probably just buying groceries and not meeting with anyone. But if she goes to a bar called the Regal Beagle, there's a good chance he is meeting someone -- maybe Larry.

Reap the Spoils
If you want to spy for cash, PI's charge anywhere from $40 to $120 an hour. Make sure to collect a retainer from the client to ensure payment prior to your investigation, because if you catch the spouse cheating, the client isn't going to be happy; and if you don't catch the spouse cheating, the client also isn't going to be happy.

Getting a License to Sneak
To be a PI you need to be licensed by the state in which you are investigating, with the exception of the following seven states: Alabama, Alaska, Colorado, Idaho, Mississippi, South Dakota and Wyoming. A license will allow you to gain access to subjects' driving records, which provides their full name, address, previous addresses, any liens on their property, social security number and their driving information. Once you've got that information and your license in hand, you can sit in your car outside of a subject's house, as long as it is a public street and the police don't think you have crossed the line between standard creep and vile reprehensible creep.

Colin Burke is a certified private investigator living in Phoenix, AZ.