Vue.js is a popular JavaScript framework that is designed for building user interfaces and single-page applications. If you are a beginner looking to get started with Vue.js, it is essential to understand its core concepts and structure. This comprehensive guide will walk you through the basic principles of Vue.js, including its reactivity system, components, and lifecycle hooks. By the end of this guide, you will be equipped with the fundamental knowledge needed to create dynamic and interactive web applications.

To begin your journey with Vue.js, you'll first need to set up your development environment. You can either include Vue.js via a CDN or install it using a package manager like NPM. After setting up, familiarize yourself with the following essential concepts:

1. Data Binding
2. Directives
3. Components
4. Vue Router

Vue.js has gained immense popularity among developers due to its versatility and ease of use. To enhance your development workflow, incorporating the right Vue.js components is essential. These components not only streamline the development process but also improve the overall application functionality. Here are the top 10 Vue.js components to consider:

1. Vuetify - A powerful material design component framework that simplifies the development of responsive applications.
2. Element UI - A desktop UI library that is particularly popular among developers working on web applications.
3. Vue Router - Essential for handling navigation in your Vue.js applications.
4. Vuex - A state management pattern and library that serves as a centralized store for all the components in an application.
5. Vue Devtools - A browser extension that provides rich debugging opportunities.
6. Nuxt.js - A framework for building server-rendered Vue applications with ease.
7. Vue Async Computed - Allows asynchronous computation in your Vue.js components, perfect for fetching data.
8. Vuex ORM - A plugin for Vuex that allows developers to manage relational data in Vue.js applications.
9. Vue Select - A highly customizable Vue component for selecting values.
10. Vue Clipboard - Provides a simple way to handle clipboard actions, making it easier for your users.

Building a responsive app with Vue.js involves a combination of effective design principles and smart coding practices. To start, ensure that you utilize Vue.js official documentation as a foundational resource for understanding the core features and capabilities of the framework. When designing your app, consider implementing a mobile-first approach, which focuses on creating a great user experience on smaller screens before scaling up for larger devices. Employ CSS Flexbox and Grid Layout for responsive design, allowing your app components to adapt fluidly across various screen sizes. Additionally, make use of dynamic classes and styles in Vue.js to enable conditional rendering based on the viewport size.

Another crucial aspect of building a responsive application is testing and optimization. Utilize tools like Google PageSpeed Insights to analyze load times and responsiveness on different devices. Incorporate lazy loading for images and components with the help of Vue's built-in v-lazy directive to improve performance. For a seamless experience, leverage Vue Router to handle navigation efficiently, ensuring users can transition between views without long load times. By applying these tips and tricks, your Vue.js app will not only be responsive but also provide an engaging user experience across all devices.