There is a whole industry of visa agencies to help you with the visa process. Some of these agencies are legit and can help you navigate the process. Some may be looking to charge you a lot of money for something that you can do yourself for little or no fee. The key is to do your research before using them though. A quick Google search can often reveal whether other travelers have had positive experiences with specific agencies.
As you begin to think about funding sources for your educational and living expenses in the United States, remember that you cannot count on working in the United States unless you have been granted a teaching or research assistantship. Immigration regulations are very strict with respect to working while carrying a student visa, and when you submit evidence of your financial resources, you cannot rely on potential income. The income on which you base your application must be assured, and it must be equal to or exceed the costs of the first year of your studies.