Figma

https://www.figma.com/best-practices/

Smart Selection + Tidy Up - https://www.figma.com/blog/introducing-smart-selection/

Frame vs Group

https://www.reddit.com/r/FigmaDesign/comments/of5dz7/why_you_should_use_frames_not_groups_in_figma/

https://www.figma.com/best-practices/groups-versus-frames/

Guides

https://help.figma.com/hc/en-us/articles/360040449713-Add-guides-to-the-canvas-or-frames

https://www.youtube.com/watch?v=0xafhHNEsp8

You need to enable the rulers first, with Shift+R.

Layout Guides

https://help.figma.com/hc/en-us/articles/360040450513-Create-layout-guides

The Figma feature "layout grid" has been renamed to "layout guide" as of May 2025, and is a different feature from the grid option in auto layout.

https://www.figma.com/best-practices/everything-you-need-to-know-about-layout-grids/