Complex VBA Excel - Best Practice (KISS)- Visual Diagrams-Wireframes or Recommendations

[aes35]

Frustrated quickly when getting 40 lines of VBA down to learn it can be written In 2 lines going a different route. 

Recommendations for the best practices on CLEANIEST way possible for Excel VBA objects, properties, and methods being applied. Simple right. Excel allows the nesting >64 levels within a function, everything become complex at a point :) MUST use Excel VBA per requirement.

Trying to locate the simplest "diagram/mapping/structure" reference guide to assist with 'order of operation' when it comes to using VBA within Excel data types are stored procedures, Access tables, and Excel worksheets/books!

Example:
- Workbook with 15 worksheets (SOME cells/columns/rows of data are being used in a variety of functions) from them all
- Different arrays, formatting, tables, charts, functions, starting points, on each worksheet in workbook
- Additional workbook with some additional data, functions, calculations to be leveraged
- Create Report/Result Worksheet file in location 'X'
- Title Report/Result Worksheet '______'
- Protect Report/Result Worksheet from being broken by end user that NEEDS the excel version!
- 5000+ lines of VBA code
Excel is powerful trying to keep it SIMPLE, ORDERLY is the goal!
Visual - Mappings of Best Practice - Order of Applying all the check, applying references correctly, looping as to not cause performance hit when loading

[#2]

@aes35 What is your question? 

[#3]

@Ingeborg Hawighorst 

1. I was asking for references visual learning aids for some aspects of the VBA (Objects) 

2. Is there any recommended method or order to adding: If you have multiple Date and/or CboBox options for individuals to select data to populate Excel VBA worksheet coming from variety of data sources leveraging VBA functions, actions, etc.

functions, forms and/or modules...
Functions within functions within functions
Ifs within Ifs with in Ifs

Or is this basically what your preference is.... I am trying to identify issues that could cause the code to CRAWL thru some looping and functions crossing active workbooks.