You want to start organizing tests from day one, right? Or, if you already created your tests created, 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); as your project grows and you have more testers, having a well-defined list of labels will 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 they exercise the most critical use cases.
• Classify your Test Sets, similar to what you did for Tests.

Organize Tests for regression testing

• You can create a Test Set for this purpose, label it accordingly (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 plus the 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.