There are two kinds of contracting: independent and brokered.

Independent means you are a freelancer. You go out and find your own clients, do the work, handle the billing, pay the quarterly taxes, obtain insurance, and so forth. Basically, you are a one-person business. You might earn 30% more per hour than a brokered contractor, but you have to deal with the business headaches and perform your own marketing.

Brokered means you work for another company that does sales & marketing and finds you the job. They find the client, you do the work, and they take part of the billable rate as a commission. As with any middle man, contracting agencies can be unethical. However, there are honest ones and they can be quite helpful.

The are several benefits to working through a consulting agency. Although they take a cut, they can keep you employed more months out of the year because of their extensive contacts. While you are working with the client, the folks back at headquarters are looking for new clients. You can think of them as your agent: you’re paying them to market you to prospective employers. They will also take care of your payroll taxes, provide health benefits, and offer a 401(k) plan. They will also intervene on your behalf if you have trouble with a client.

Most contractors are in their 30s or older. The reason is you must have experience that companies want. You’ll find some in their 20s, but they must be careful not to be pigeonholed as “that Java guy” or “that Oracle gal.” You have to be constantly learning and growing. Startups are good places to hone your skills because you have a lot of freedom to experiment with technologies that catch your interest, and you typically don’t have businessmen telling you what tools to use.

Contracting can be desirable if you like novelty. You get to move around, meet new people, and see different work environments. Politically, contractors are nearly always on the bottom of the totem pole because you’re “just a temp.” You won’t have any staff, budget, or equipment. On the other hand, you are less likely to get embroiled in office politics because you’re there to accomplish a specific project, and people know that and leave you alone.

You must be a good communicator and not feel embarrassed to ask for help. If you are at a company as a contractor, if often means something is already behind schedule or not working properly. Therefore, you’ve got to get in, figure out what’s going on, and then try to patch things together, even as people around you are anxious.

You also have to learn quickly. Often times you’ll be hired for one thing, but then the project will require something else you’ve never used. It is also typical for the project to be poorly specified, so you must take the initiative and seek out people within the organization who can assist you.

The pay can be good: often times you will make twice the rate of employees at the client company doing similar work. However, there are gaps between gigs when you’re “on the bench.” Because of bench time, you have to be disciplined financially. Some months you’ll get fat checks, but you have to remember to save them and stick to your budget because there will be lean times. Some contract houses pay for bench time (up to a certain number of weeks), but I wouldn’t count on it.

Another thing to keep in mind if you decide to work with more than one agency is that you must never let anyone submit your résumé without your permission. The reason is that if a client receives your résumé from multiple agencies, she will reject you because she doesn’t want to argue with the agencies about who gets the commission. An ethical agency will never submit you without asking first. In addition, if you are working with more than one agency, recruiters will often ask you where else you have applied. It is OK to let them know so they don’t accidentally double-submit you.

You should list technologies on your résumé you’ve worked with regularly for more than six months. The old “one page” rule doesn’t apply anymore, especially for tech workers. It should be more like a yellow pages advertisement—I can do this, this, and this for my clients. It should also list specific accomplishments, preferably with a dollar amount because it shows you understand that IT is to serve the business and make it money. For example: “Installed robotic storage system that freed up 2,000 sq. ft. of factory space, saving $630,000 per year.”

I also recommend getting a small box of business cards from a company like 4by6. They don’t need to be anything fancy. They should have your name, phone number, email address, and a headline that describes what you do.

I’ve had no luck with Monster and Career Builder since they are too broad. You’ll have a better experience with a tech-centric site such as Dice. I’ve gotten interviews with desirable companies through LinkedIn as well.

Further Reading