I use coding agents daily, but how do real engineers use them?

I have a broad but shallow technical background (longtime management consultant) and use agents (a variety of services and models in VS Code) extensively for my own projects. I know I'm hitting a ceiling. My workflow is naive and nonpro, a lot of tinkering and bashing my way through code generation, context drift, manual fixes, etc.

I want to learn how senior engineers treat these tools. Processes, systems, guardrails, must-dos, etc.

If you write code for a living and have integrated agents into your workflow, what does your system look like?

Any/all input is welcomed: resources, URLs, outlines, warnings, discoveries, recommendations.

None of these are specifically needed, but ideas?

-How do you structure a brand new project? Scaffolding, git init/ignore? Repos? Initial commit strategies? How do you keep stuff out of the context window that you don't want in it?

-How do you "layer" your work so it's much more about the context and integrity of the structure and much less about prompts?

-Do you switch models (often? ever)? Why?

-What other tooling do you have alongside basic agents/environments?

-What are "pro habits" that I don't have and should?

-Any suggestions for how to work in a very domain-specific endeavor to try to increase the utility of the agents for a silo like this?