Consistent style is important. One of the more prominent style guides for Vim is the one published by Google: https://google.github.io/styleguide/vimscriptguide.xml. It highlights some common development practices and outlines common pitfalls.

Here are some excerpts from the Google Vimscript style guide:

• Use two spaces for indents
• Do not use tabs
• Use spaces around operators
• Restrict lines to 80 columns wide
• Indent continued lines by four spaces
• Use plugin-names-like-this
• Use FunctionNamesLikeThis
• Use CommandNamesLikeThis
• Use augroup_names_like_this
• Use variable_names_like_this
• Always prefix variables with their scope
• When in doubt, apply Python style guide rules

Give the Google Vimscript style guide a read, it's rather useful even if you never plan on doing more than customizing your .vimrc. It'll help with self-consistency.