You want to start organizing tests from day one, right? Or, maybe you already have your tests created and it's time to organize them. 

Organization should start by classifying your tests individually, so you can easily find and filter them out.

At Test level

Classify your Tests

• use labels to tag your Tests (or your Test Sets); if you start having many testers and your project grows, having a well-defined list of labels may help
• use the priority field, so you can distinguish between tests
• assign the Test to the proper component

Using Test Sets

Organize Tests in Test Sets

• group tests in as many Test Sets as it makes sense to you, either because they're testing the same feature or the same UI component, or if they exercise the most critical use cases
• classify your Test Sets, similarly to what you did for Tests

Organize Tests for regression testing

• you can create a Test Set for this purpose and add a specific label to it (e.g., "regression"), and then you test for covered issues of previous versions
• you can create a "regression Test Set" for each version by adding the previous version regression test set tests and then new tests

Example: You're working on product v3.0 and want to do regression testing to make sure you have not broken anything. If the previous version, v2.0, had already some regression tests in a specific test set, then you can add all tests from that specific test set and all the ones for validating v3.0.