Cross-posting from my Facebook post but wanted to know what would be the best advice you would give a newcomer to Editor X.
always use grids and dockings, haha
Hey Roberto!!
Here is my take on some best practices!
1 - Design Section by Section 
Avoid designing all sections on the primary breakpoint to then make adjustments into smaller breakpoints.
Best approach is to go section by section design from largest to smaller breakpoints, AKA Jack the Ripper Approach.
Why?
You want to decide structure and component use before we start designing… are we using Grids? Layouter? Repeater? How is the design going to shift in order for you to decide the best component and structure?
Always think of the UX and what is the best layouting tool to accommodate that experience.
2- Always Start on Primary Breakpoint (Desktop) 
I know, mobile first for our UXers is the rule, but when working on Editor X we’ll use the Cascading Rules.
If you are using a prototyping tool you can import the largest breakpoint frame from Figma to Editor X
Here is more about that Beta plugin:
https://www.figma.com/community/plugin/987294632651817123/Editor-X
3 - Use that Drag Handle until you are tired ↔️
As you add your elements on primary, always check for responsiveness on smaller breakpoints. A well designed section can always be saved as an asset to be reused, speeding up that build process.
More about design assets
https://support.wix.com/en/article/editor-x-saving-and-reusing-design-assets
4 - Performance and Design 
Reality is every component you add ads to loading time. That’s Facts!
But still we can be mindful of our design choices to optimize the UX
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Adding media to section weights less than stretching image on background. (I need to verify this info, but seems legit)
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The simpler the structure the faster is the loading (more levels in hierarchy and content means longer loading time)
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Design optimization on Editor X https://www.editorx.com/shaping-design/article/website-optimization-editorx
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Mobile First Trend https://www.editorx.com/shaping-design/article/mobile-ux-design-tips
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How website loads https://support.wix.com/en/article/site-performance-how-wix-improves-your-sites-loading-time
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Caching https://support.wix.com/en/article/site-performance-caching-pages-to-optimize-loading-speed
These are awesome tips. Will add them to the collection of posts.