Yesterday I stated my opinion that if you can't cut A/B grades in high school that you probably shouldn't go to a 4 year college. But what should you do if you don't have very good grades in school?
Below I've listed a variety of career choices that might be good areas to go into. Most have wages around $40k average. These are just some semi-random suggestions. Its really up to you to decide what to do with your life. If you don't know what career you should pursue then I'd recommend going to your library or counseling office / career center at school and getting all the books or material you can about career choices. Figure out your strengths and match that to a job that you think you might like and you can make a living at.
Variety of career choices for those without a 4 year degree:
Real Estate agent - Median wages are about $40k. You have to pass certification training and you have to be competent at selling. Income can be very inconsistent and you may have little or no guaranteed salary. Hours may vary significantly.
Military - Joining the United States Military is a pretty good career option for a number of reasons. Members of the military provide an invaluable service to our nation. The pay is not fabulous starting out but there is good potential for promotion and plenty of benefits. There is the obvious danger related to the job. Another big benefit of the military is that it can give you the experience to open the door to many civilian jobs.
Skilled Construction : Electrician, Plumber, Sheet Metal worker, etc - Skilled workers in construction can make very good wages and can have good benefits. Electricians and plumbers both make abut $22 /hr average. Union positions generally have higher wage levels and benefits. Formal apprentice programs will give on the job training as you are paid to learn. This work can be dangerous and may be outside in harsh weather. Construction work is also very dependent on economic cycles.
Car Salesman : A job in retail sales generally won't require a degree. If you have an aptitude for sales then you might do well as a car salesman. The median hourly wage for auto sales is over $18/hr. Your wages will depend greatly on your ability to sell. If you feel you have a knack for sales then you could try it short term and you'll know if you can succeed at it or not pretty quick (cause they'll probably fire you if you can't).
Work up to Management - This isn't a job you can instantly jump into but a career path that can lead to a highly compensated position. Most service industry employers have career paths to promote people form entry level positions to management roles.
Air Traffic Controller - This is a hard job to get into and there are not many openings. If you don't go to special school or get training in the military then you have to be 30 years old and have some work experience. The work difficult and is extremely stressful. But if you can cut it then the compensation is good with average wages well over $100k.
Postal mail carrier - Median wages are over $49k. Benefits are pretty good. You have to score well on the postal exam and jobs are going to be harder to come by. Competition for postal carrier jobs is going to be keen in coming years. You have to work outside and early hours.
Auto Mechanics - There are a lot of cars out there and they eventually break down so there are a lot of opportunities to work as an auto mechanic. Median pay is a bit over $16/hr. Training varies but usually includes some form of vocational post secondary certification. You may go to a community college for an associates degree. Many auto makers and dealers sponsor programs to train mechanics in work and study rotations.
Paralegals and legal assistants - Most paralegals have a 2 year degree but some are trained on the job. Paralegals make $46k median wages. The work is indoors but might have long hours and stressful environments. Demand for paralegals is growing.
Hazardous material removal - This is the kind of job where you suit up and wear a mask to remove asbestos or other hazardous materials. There is no special education required but you might need certification. Wages are pretty good with median pay just short of $18/hr. Of course you run the risk of exposure to the hazardous materials but if done properly it should be fairly safe.
Dental assistants - You generally learn this field on the job. This is not to be confused with a dental hygienist which is a higher level occupation. The dental assistant is there to be an assistant by performing various duties in the dental office. Median pay is about $32k and job prospects are good.
Correctional officers - Guards make about $38k median wages. Some positions may require a college degree and others may not, so you may have to look around. I'm not really sure how dangerous these jobs are exactly but truck drivers and farmers die on the job more often than police officers so don't assume too much about the risk factors.