I was a solid DIII distance runner. After graduation I stayed in the area and worked a couple of different day jobs and was a volunteer with the team for a year.
Was offered a PT assistant position at the same University. (luckily I was able to help coach a few All-Americans in my event group distance)
It was fun but financially it just wasn't feasible to continue. I was barely scraping by working as an insurance agent, electronics salesman, and in an on campus dining hall. The last job was to help me from going hungry too often.
I quit coaching and got a nice paying job relating directly to my major and was making about $35k but absolutely hated it. I reevaluated what I wanted to do with my life, what skills I actually had and came to the conclusion that I should go back to coaching. I got USATF level 1 certified and got my meager resume together.
I applied to 100s of job openings with no luck. But eventually was hired as a PT assistant at a mid major D1 University.
I started out just holding the stopwatch for the other coaches but after a year or so eventually started coaching my own small event group. (jumps and sprints)
I got USATF level II certified in sprints hurdles and relays to help with coaching my new event group.
Distance runners were getting hurt constantly with the coach in charge of that group and he started unloading these athletes on me to try and get them fit and healthy. My entire new group got healthy and ended up running significantly faster than the healthy distance group that remained with the distance coach.
I was moved to distance coach the next year and given a nice raise.
Over the next 5 years I was given pretty steady raises and improved job titles just by getting solid results and being a positive person to work around. I went from a part time contract to a full time contract then was given the title of Cross Country Coach with another raise and am currently Cross Country coach as well as Associate Head Coach for Track.
Some of you are probably interested in income progression mine was like this...
0k Volunteer DIII Assistant 1 year
3k PT DIII Assistant 1 year
13k PT D1 Assistant 2 years
19-24k FT D1 Assistant 3 years
31-34k FT CC Coach 2 years
50k+ FT CC Coach/ Associate HC Track 1 year
My advice for people who want to become a D1 coach would be pretty much garbage as I basically just got really lucky with getting my foot in the door at a D1 when I was young (24).
However...
My advice for keeping your job as a D1 coach (after seeing 7 different track coaches come and go during my 10 years coaching) would be to have a presence on campus (don't just come to work do your job and go home) go to volleyball games, soccer games, basketball games. Smile and say hello to everyone you see. Go to events that aren't mandatory and have a smile on your face while you're there.
Most important be good at what you do. Be analytical, if you're average athlete improves 7% from HS and you have someone struggling to improve 3% meet with them ask them what we could be doing different, play with different volumes/long runs/workouts/frequency of competition etc... The day you think you have it all figured out is the day you stop getting better at what you do.
tl;dr version...
Volunteer, work for free if necessary to get some experience.
Take any job you can get early on. You will get paid next to nothing.
Show you're continuing to learn in the sport. (USATF schools, USTFCCCA programs)
Have a positive attitude.
Most importantly be good at what you do. If only half of your kids are faster than they were in HS it might be time to reevaluate what you're doing from a training perspective.