After graduating high-school, I did not attend a university and instead decided to enter the work force. Eight years hence, I would like to pursue a university degree but I am not entirely sure which credentials are important for an adult freshman. Are my high-school transcripts still relevant almost a decade after the fact? Do universities consider professional experience in their admissions process (I have 6 years professional experience related to my intended field of study)? Do I have a shot at competitive university even though my academic history is essentially nothing? With sufficient review, I expect I can achieve high standardized testing scores, but I wonder if that will be enough to compensate for such a huge gap in my academic career.
The crux of my question is: how should an adult freshmen prepare before applying to a competitive university?