The nature of transfer credits as they exist within the education industrial complex today means I have to take English Composition 101 - even though I have a BFA in Graphic Design, worked at a newspaper for over five years (as a graphic artist and as a writer), not to mention the numerous reports and citations I needed to generate while in the Army.
Prepare yourself to take remedial classes, unless the credits you earned taking online classes while in the service are compatible at the institution of higher learning you are going to attend.
Many universities have a series of placement tests for mathematics courses. I highly suggest visiting Khan Academy if your math skills are a little rusty. Hopefully you will have at least 30 days to brush up on Algebra before taking a placement test.
Sitting in a classroom with students fresh out of high school can be a little frustrating on a number of fronts. The students in my English 101 class are rather timid and the professor has to cajole them into participating in discussion most of the time. I used to tacitly wait for a few seconds before offering my opinion; until I decided the long, uncomfortable silences might encourage someone else to reply first. This tactic changed nothing and the professor now randomly calls a student for a response.
Every class at my university has a syllabus. Every syllabus details the class schedule, the assignment schedule, and the details for the assignments. You can maximize your time by reading the syllabus objectively and making a plan. You should have a pretty good feel for the amount of effort you will need to put into each class by the end of the second week.
Many of the assignment descriptions refer to what it takes to earn a "C" grade, meeting the standard. Suppose the assignment is to write a 1200 word essay on transfer credits, with a list of works cited at the end. If you want to meet the standard, simply do an internet search for transfer credits and string a few paragraphs together. If you want to exceed the standard, use excessive details about transfer credits - what they are, who accredits them, how the creditors relate to one another, who transfer credits affect and why they exist.
Many universities have tutoring available. Use the tutors. They are typically graduate students who need some experience while pursuing their teaching degree.
Utilize the library. Many libraries pay an exorbitant fee for access to millions of documents on other networks and platforms. Your tuition is where the library gets the money for that service, so use it. Many libraries are also staffed with graduate students who are there to assist you in finding research material and they may even go so far as to help you narrow down a research topic.
It would have been nice to have an option for testing out of English 101. I made the most of it and used it as a way to practice writing within the guidelines of an assignment, improve my research skills, and get used to the fact that there is now a burdensome need to cite nearly every idea, tangent, or fact that you use.