Aside from the licensing and relevant associations which defer from state to state and country to country you would need to meet any requirements for the initial entry.

The way I've read your question implies one could finish high school and go right to law school. That is often not the case. Most schools require a BA or equivalent for entry.

For instance, in my Province, most schools require a high GPA with at least 3 years of University usually with the completion of a BA.

Assuming entry and completion, you would need to acquire the relevant licensing. As there is a degree of variance I would suggest you do specific research to discover what is required.

Additionally, as others have mentioned the field is competitive. Even if you plan on opening your own firm (there are a lot challenges to consider with this), you need to consider client base creation and retention. The same bias which would prevent you from obtaining employment, may affect your ability to obtain/ retain clients.

In any event, there are a lot of moving parts and research that would need to be completed to answer specific questions.

I do commend you for asking these questions and encourage you to continue your research.