"Networking" is an overused word that means "talking to people." Networking is probably how you will get your next job, and once you're there, your networking will help you make business connections that will help you succeed. At its simplest, it means casually keeping in touch with old friends as your careers mature. At the other extreme, "networking" can be an active, highly focused, goal-oriented process designed to get you the job you want. Both casual and active networking are important, and they work together.

Casual networking with old friends and acquaintances is something you should never stop doing. As your mother probably told you when you left for college, "you should write home more often." Keep in touch with your friends, grad-school classmates, and professors after you, and they, have moved on.

• Email makes it easy to keep in touch. But for networking purposes, try to be somewhat discrete: don't send chain letters or incredibly offensive (but funny!) internet humor to your whole network. Write to say hello, send interesting articles or links, and send updates when you move. I sometimes even send my holiday letter (the one I send with Christmas cards) by email.
• Lunch with "old friends" is one of the best ways to catch up. Make a New Year's resolution: have lunch once a month with an old friend who works elsewhere.
• Don't forget your graduate lab. You can always go back for great seminars. I like going to my advisor's summer picnics: she has great barbecues in the corn field where she does her genetics work! Another popular way to maintain this connection is goodies I've cleaned out my lab at work and found thousands of dollars worth of slightly expired reagents that need to be disposed of (can't use them for regulated work), and have found that academic labs often don't really care if their reagents are a little old, as long as they still work.
• Maintain confidentiality. Your old co-worker may be your best friend and surf-buddy, but if she is at another company now do NOT forget that your company's secrets are confidential. Nobody will think well of you for violating your own company's trust.
• Your casual network is a great place to start your active network.

Active networking takes more effort, and is the most certain way of finding a job. It also builds on the casual networking that you've been doing all along. The goal is simple: you want to talk to as many people as possible in the companies, field, and town where you want to find a job. Your goals are to learn about the company, introduce yourself, and to get names and introductions to 2 or 3 additional contacts. That's why its called networking, after all"if you talk to 2 people, and they each give you 2 more contacts, and THEY each give you 2 contacts, soon you will have met dozens of people throughout the area you want to work.

• Avoid pressuring your contact for a job: they'll ask you for a resume if they are interested, don't worry. The easiest way to get a quick brush-off is to come across as just looking for a job opening.
• Use the phone heavily, but by all means go "have coffee" if you are invited.
• Realize that every interaction you have with anybody at a company you could work at is a potential job interview. Even if you never discuss job openings, your contact may consider the informational chat a "pre-screening" job interview.
• Ask questions. Ask about how the company is organized, who the competition is, and what the long-term strategy is. Ask personal questions, about your contact's training and career path, how they got promoted, and what they like and dislike about their job. And ask about the diversity of opportunities at the company, what different career tracks there are, different job categories, other departments.
• When you call, introduce yourself briefly and explain why you're calling. Tell your contact who gave you their number, and that you are interested in learning more about their company. Practice a two sentence biography, don't read your resume over the phone.
• Remember to ask for additional contacts. Most people won't offer other names unless you ask them directly. "Do you know anybody at XYZ Corp.? How about a manager in the ABC department that you mentioned?" Ideally you will get a name and a phone number, plus your contact will give them a heads-up call so that you won't be calling out of the blue.
• Read the latest version of What Color is Your Parachute, an excellent book on job seeking and networking.

Finally, remember that networking is a two way street. When someone calls you, take the time to chat. If someone calls asking you for a job, explain that you're not necessarily hiring right now (even if you are), but that you are willing to talk more generally about the company and industry. Whether you call it the golden rule, karma, or you're just trying to get that referral bonus, it feels good to help others.