Opportunities are open but you will have to achieve them. Pay off all your bills now, such as a car payment or anything similar. You will want as much money saved up for school with as little debt payments as possible.
While in school, stay focused on learning the material in your classes. Older students are often very focused and motivated. Allow the negative aspects of your military experience to motivate you to get your homework done when things get tough.
It does not matter what age you are. It matters what skills you possess. Learn everything you can in school and you will set yourself up nicely.
Follow your interests in selection of your major. This tends to be heavily influenced by teacher/professor quality.
University of Illinois at Urbana/Champaign, my alma mater, is a very tough school with a more theoretical direction and I question if the increased theoretical difficulty is worth it in comparison with other universities for military veterans studying to get into the workforce rather than for theoretical pleasure.
University of Illinois at Chicago is easier than UIUC while teaching in a strong and practical direction. I studied here for three semesters and enjoyed it. UIC seemed to be better suited for me than UIUC.
Southern Illinois University has a reputation for being a party school but they seem to have a solid curriculum since I have been impressed by a few of their graduates.
Northern Illinois University is a solid option, especially for business, but their computer science curriculum left a lot to be desired when I looked at them 10 years ago.
NorthEastern Illinois University appears smaller but their course direction seems solid. I know a few good people from there.
I question your direction towards law, give that some more thought. However, law is a graduate program anyway. You first need to get through a bachelor's degree.
To add onto the government possibilities, the FBI likes agent prospects with a military background. Your experience would provide you with many opportunities with the FBI. Add an accounting or engineering degree to your military experience and they get very interested. I considered the FBI but came to the conclusion that I had spent enough time in service to this country after 6 years in the navy.
http://www.fbijobs.gov/