Build a portfolio
This doesn't have to be an extensive portfolio.
1-3 songs that you can record, mix, and get sounding pretty decent will do the trick.
Well... how do you do that? What if you don't have anyone that will pay you to work on their music yet?
Work for FREE.
You may have to go out on the town and find bands you like and ask them if you can help them record a demo free of charge.
That's exactly how Joey Sturgis who I mentioned above got started.
He didn't even have his own studio yet! He used a friends garage and recorded a band that would eventually get signed.
He did this for free or for less than $100 I think.
My point is... to gain experience and to get people to trust you with their art you have to make it a risk free option for them.
Worse case scenario they hate your work and they didn't pay a dime. They shelve it. You gained some hard earned experience and keep working to get better for the next time.
Best case scenario they get a bad ass demo cut and you get experience, and something to add to your portfolio. They spread the word and you get new opportunities.
Next time you work with them you can charge for your services, and if you did a good job they will be happy to pay.
If you have your own band, use them!
Network
I can teach you how to become and audio engineer and the skills you will need, but what kind of engineer do you want to be?
Do you just want to make your own music. Thats fine... if that's all you want to do.
But, if you want to learn how to become an audio engineer because you want to do this for a living then you need to network.
Don't just hide in your bedroom or garage.
Go out in your local music scene and meet people.
Hang out where musicians hang out. Don't be too pushy, but slowly let them know you know how to record and mix and would love to work with them.
A lot of opportunities come from people you know and connections you make.
The truth is, sometimes people who are not the most qualified get the job because they are connected.
They built friendships and met people who knew other people who would recommend them.
As long as you can get the job done and make a product that's decent you can go a long way with some networking and building relationships.
Find an Internship
These are harder to come by these days, but find a local recording studio and ask if you can help out. For free of course.
I got experience by doing this at the Zone in Wimberly, TX.
I had a connection to Pat (who I mentioned earlier) because I had recorded a record there with my band years earlier.
I asked if I could come sit in and help out.
I made coffee, helped set up mics, got lunches for the band, and anything they asked of me.
I also watched Pat, a grammy nominated engineer, work with a major band and I gained invaluable experience.
So get out there!