Getting started with Django is an exciting journey into the world of web development. Django is a high-level Python web framework that simplifies the process of creating robust web applications. To set up your first web application, you'll need to begin by installing Django. First, ensure that you have Python installed on your system. Then, you can easily install Django using pip, which is Python's package manager. Simply run the command pip install django in your terminal or command prompt. Once installed, you can verify the installation by checking the version with django-admin --version.

With Django installed, you’re ready to create your first project. Open your terminal and run the command django-admin startproject myproject, replacing myproject with your desired project name. This command will generate a new directory containing the essential files to get your application up and running. Navigate into your project directory using cd myproject and start the development server with python manage.py runserver. You can access your new web application by visiting http://127.0.0.1:8000 in your web browser. Congratulations! You've successfully set up your first web application using Django.

Building scalable web applications with Django requires adherence to certain best practices that not only enhance performance but also ensure maintainability. One of the top practices is to follow the DRY (Don’t Repeat Yourself) principle. This implies that you should encapsulate common functionalities into reusable components, such as mixins, custom template tags, or middleware. By doing so, your code becomes cleaner and easier to maintain. Additionally, consider structuring your project using the MVT (Model-View-Template) pattern that Django promotes, which separates the concerns for better organization and scalability.

Another crucial best practice is leveraging Django's built-in caching mechanisms. Implementing caching can dramatically improve the response time of your web application, especially under high traffic conditions. Utilize cache frameworks like Memcached or Redis to store dynamic content, thus reducing the load on your database. Furthermore, employing proper database indexing and optimizing queries will enhance data retrieval efficiency. Finally, always keep your dependencies up to date, and periodically conduct performance audits to identify bottlenecks, ensuring your application scales seamlessly as usage grows.

Debugging Django applications can often be a daunting task for developers, especially when dealing with complex codebases or unexpected behavior. To effectively debug Django applications, it’s essential to familiarize yourself with common issues and tools that can assist in troubleshooting. First, make sure to enable the DEBUG mode in your settings.py file. This feature provides detailed error pages, complete with traceback information that can point you towards the root cause of a problem. Additionally, utilizing built-in logging can help capture runtime information, making it easier to trace back through your application’s execution flow.

Another valuable tool for debugging is the Python Debugger, commonly referred to as pdb. By inserting import pdb; pdb.set_trace() in your code, you can pause execution and inspect variables at that point in time. Furthermore, consider leveraging third-party packages like django-debug-toolbar, which adds an interactive panel to your web pages, providing insights into SQL queries, cache usage, and much more. Here are a few more tips to enhance your debugging process:

1. Utilize assert statements to validate your assumptions in the code.
2. Check for any migrations that may not have been applied properly.
3. Use print statements strategically to isolate issues.