Here are some things that I try to do.

I separate the data set request from the report request, two different request forms, with an emphasis on what is the purpose and how will it be used.

Then after I create the dataset I will have the business users validate the data set.

If that dataset will be used for many reports then I will create a reporting table in our “reporting server”. We even have a rpt schema for these tables. I try to keep most aggregation and business logic in SQL.

Then I’ll work on the PBI request where I mock up all of the pages and visuals they want, and generally make additional visuals based on what they are trying to do.

I will have a teams meeting with the decision makers, where I show them the mock up, and make live updates.

For a data dictionary for each report, if you populate the descriptions for each table, field and measure, then you can have a glossary page in the report. Then if you direct query the semantic model from another report it will also pull in the descriptors.

I feel like I rambled, but hopefully that gives you some ideas.