- Be a good developer--all the advice and best practices for software developers still applies to you. Much of your job will be coding automation, test suites, integration tests, etc. All the best practices of writing solid, readable code will definitely be useful to you.
- Work closely with your fellow developers. Have them code review their checkins with you so you understand how their code works. Find out what they think are risky areas to target. Help them understand how they can write more easily testable code. Don't fall into a trap of developers throwing code over the fence at test, and test throwing bugs back at them. Everyone is in it together to ship a quality product.
- Understand how your customers use your product and make sure their usage is covered in your tests. It's easy to look at a spec and start trying to test all of the inputs, edge cases, etc. It's better to understand how your customers/partners will use a feature and make those your highest priority tests.
- Try to catch bugs as early as possible. Automate your test execution, run test passes against changes/checkins, and alert yourself when changes cause new test failures. If you let too many bugs get into a build you'll waste tons of time sifting through hundreds of failing tests to find the bugs.