This is the modern term for the phrase 'It's not what you know, but who you know'. Whether you're trying to find a job, change careers or get a promotion, the fundamental principle still applies - you need help to achieve your goal. Here are some tips:
Ask friends, neighbours, relatives and former colleagues if they know anyone who works in the field you're interested in. If so, write or phone the person to request a brief interview (be sure to mention the name of your contact). If she's too busy to meet you, invite her to lunch.
When you meet, don't simply announce that you're networking or looking for a job. Instead, ask about her work, her company, her career path to date and her plans for the future.
Avoid getting too personal. Your attitude should make it clear that your interest is in business.
Mention your skills in passing, but don't sell yourself. Bring a CV in case it's requested.
At the end of the conversation, ask for the name of another person you could contact. Always follow up with a thank-you note.
Remember that whenever a person recommends you, she is putting her own reputation on the line. Try not to abuse the privilege, and always offer to return the favour.