This is all real, down-to-earth advice that corresponds with my observations after three years doing this.

> A good first step is pick a specific problem and/or a specific industry

To add, I prefer thinking of three levels of specialization:

1. By vertical or industry (oil and gas)

2. By problem or technical domain (user interfaces, data pipelines, etc.)

3. By platform (Salesforce, React, etc)

2 and 3 could be conflated, but I like to separate them. Your specialization can cut across dimensions and at a small scale it's likely the best (eg: "we build custom Salesforces apps for sales processes in oil and gas")

> You can make more money doing the first but your job will eventually be 100% account management and sales.

There is not two ways about this, but emphasis on eventually... I think up to a certain scale you will be able to combine technical and management - although arguably the scale is much smaller than we'd like to think.