When beginning to explore CSS units and properties, this website can serve as a valuable resource. They provide clear explanations on which units are best suited for different elements within your design.
For instance, using em as the unit for text allows for automatic adjustment based on the user's device standard font size. Utilizing values like 2em would result in text being twice the current font size.
In addition to considering various units, it's important to take note of CSS properties such as max-width and max-height. Implementing these can prevent issues with site readability caused by excessive stretching on high-resolution displays.
Another option worth exploring is utilizing a pre-designed CSS framework like bootstrap, which streamlines the process of creating visually appealing websites quickly. While not suitable for all projects (such as those requiring specific corporate branding), bootstrap can be a valuable tool for developing user-friendly interfaces.
In terms of following "standard" practices, there are recommendations and commonly used techniques to consider. Ultimately, the direction you take will depend on your preferences and the unique requirements of your project.
I trust that this response has provided you with guidance and a solid starting point for your design journey.