I worked as a mechanic in a bike shop for a few years: we were the Trek shop for the area. While there are plenty of things the average person can do and get pretty close to correct, there were soo many tickets that came in for botched repair jobs, stripped hardware, and shit setups.
I think everyone should be able to fix a flat tire and lubricate a drivetrain. But beyond that, bring it to a person who has the knowledge and very specific proprietary tools to do the job. It's possible you can use some pliers and a hammer to do what you're doing, but you'll probably damage components and then need to bring it to a shop anyway.