docs: update contributing guide

CONTRIBUTING.md

@@ -6,7 +6,7 @@ The development requirements are listed in the `requirements-devel.txt` file. In
 pip install -r requirements-devel.txt
 ```
 
-The newest client versions sometimes require upcoming Weaviate core features. We recommend using Docker (see https://docs.weaviate.io/deploy/installation-guides/docker-installation) to run a local instance of the `latest Weaviate core <https://hub.docker.com/r/semitechnologies/weaviate/tags>`_ for client development.
+The newest client versions sometimes require upcoming Weaviate core features. We recommend using Docker (see https://docs.weaviate.io/deploy/installation-guides/docker-installation) to run a local instance of the [latest Weaviate core](https://hub.docker.com/r/semitechnologies/weaviate/tags) for client development.
 
 #### Installation
 
@@ -31,6 +31,18 @@ pip install git+https://github.com/weaviate/weaviate-python-client.git@BRANCH_NA
 If any static analysis tools such as Pylance fail, try installing the package with:
 `--config-settings editable_mode=compat` suffix. (e.g. `pip install -e . --config-settings editable_mode=compat`)
 
+### Project structure
+
+The client is organized around the v4 collections API. When adding or updating code, prefer the existing v4-style collection interfaces rather than the legacy v3 client patterns.
+
+Commonly changed areas include:
+
+- `weaviate/collections/` for the v4 collection APIs and typed request/response classes.
+- `weaviate/connect/` for connection and transport behavior.
+- `test/` for unit tests that do not require a running Weaviate instance.
+- `mock_tests/` for tests that simulate Weaviate responses.
+- `integration/` for tests that require a local Weaviate instance.
+
 ### Testing
 
 To set up the testing environment, install the test requirements with:
@@ -41,24 +53,36 @@ pip install -r requirements-test.txt
 
 There are three kinds of tests:
 - Unit tests test individual client components.
-- Integration tests use a running weaviate instance to test the client.
-- Mock tests simulate a weaviate instance to return specific values.
+- Integration tests use a running Weaviate instance to test the client.
+- Mock tests simulate a Weaviate instance to return specific values.
+
+For most pull requests, run the smallest relevant test target first, for example:
+
+```shell
+pytest test/path_to_changed_test.py
+pytest mock_tests/path_to_changed_test.py
+```
 
-To run the integration tests,
+To run the full local test groups:
+
+```shell
+pytest test
+pytest mock_tests
+```
+
+To run the integration tests:
 
 1. Ensure that you have Docker installed.
-2. Start the weaviate instances, changing `WEAVIATE_VERSION` to your weaviate docker image target
+2. Start the Weaviate instances, changing `WEAVIATE_VERSION` to your Weaviate Docker image target.
 
 ```shell
 ./ci/start_weaviate.sh WEAVIATE_VERSION
 ```
 
 3. Run the tests.
 
-```
+```shell
 pytest integration
-pytest mock_tests
-pytest test
 ```
 
 ### Linting
@@ -72,12 +96,21 @@ We use the following tools to ensure a high code quality:
 
 Note that all plugins are listed in the `requirements-devel.txt` file and are installed in the first step.
 
+Before opening a pull request, run the linters on the files you changed:
+
+```shell
+ruff format $FOLDER_WITH_CHANGES
+ruff check $FOLDER_WITH_CHANGES
+flake8 $FOLDER_WITH_CHANGES
+```
+
 ### Creating a Pull Request
 
 - The main branch is what is released and developed currently.
-- You can create a feature-branch that is named: feature/YOUR-FEATURE-NAME.
-- Your feature branch always has the main branch as a starting point.
-- When you are done with your feature you should create a pull request into the main branch.
+- Create a focused branch from `main`, for example `feature/YOUR-FEATURE-NAME`, `fix/YOUR-BUG-FIX`, or `docs/YOUR-DOCS-UPDATE`.
+- Keep the pull request focused on one change and include tests or documentation updates when relevant.
+- Run the relevant tests and linters before requesting review.
+- Create the pull request into the main branch.
 - The main branch is protected.
 
 ### Contributor License Agreement
@@ -86,6 +119,5 @@ Contributions to Weaviate python client must be accompanied by a Contributor Lic
 
 The process works as follows:
 
-- You contribute by opening a [pull request](#pull-request).
+- You contribute by opening a [pull request](#creating-a-pull-request).
 - If your account has no CLA, a DocuSign link will be added as a comment to the pull request.
-