The characteristics typical of a good private investigator are not unlike those found in the Boy Scout oath:

"A good private investigator," says Nicholas Beltrante, "has common sense, inquisitiveness, integrity, dedication, persistence, ingenuity, inventiveness, alertness."

And that's not all: "A good PI is clever, intelligent, a good observer and has the ability to communicate with people of all walks of life, the ability to assume responsibility, the ability to make quick decisions and the ability to follow instructions."

Numerous occupations and professions are compatible with private investigating, Beltrante points out, including police work, the law and journalism.

Beltrante says almost anyone can become a good private investigator "with the proper guidance and training." If they learn the ropes and apply themselves, he says, they should be able to earn $30,000 or more a year, plus benefits, within two or three years.

The key to getting a good start has to do with preparation and expectations:

* Think about what background you have that may tie in with work as a PI, prepare a re'sume', and don't expect to enter the field at or near the top without the prior experience to warrant it.

* Attend the monthly meetings of the Maryland and Virginia state private investigator associations.

* After writing your resume, mail copies, along with a cover letter, to prospective agencies. Follow that up with a phone call two or three days later.

* Occasionally the help-wanted columns of area newspapers advertise job openings in the PI field.

* Be realistic. Beltrante says beginners should "tell prospective employers you're not looking for top dollar," that you're looking for an opportunity to show your ability, you're certain you can prove yourself in a short time.

"I can tell you a person coming in on a part-time basis will earn somewhere between $7.50 and $12.50 per hour, based on what they have to offer," says Beltrante, who gets from one to five job inquiries a day.

The real money comes after the PI has gotten a few years' solid experience under his belt. "Then," says Beltrante, "you go out and start your own agency," even if you're operating a single-individual business. That's where you going to make the money. "In my case, I'm charging my client $50 an hour [for his employe's time], and I'm paying my investigators $10, $12 or $15 an hour. You can see what the markup is on that per-hour amount."