TL;DR: Notes on how I’ve been organizing pages for my Wikidata WikiProjects. These are for my future self but could benefit others too. Suggestions welcome!

NOTE: This is about topic related projects, community WikiProjects like WikiProject India would have different needs.

In the last six months, I have created three Wikidata Wikiprojects with different sizes, depth, and completeness. After rounds of trial and error, I have learned of useful Templates and ways of organizing these pages. Having a good WikiProject page is like having good code documentation, it helps me remember what I wanted to do even when I come back after a month of being inactive. Here are my building blocks:

Introduction

Explain the domain of the project using the P and Q templates. If there are sub-pages with tables (more on this later) I try to list them here, but I am not yet sure if this is a good idea. See the intro section of the CJI project for an example.

Queries

Hoping the reader scrolls at least to the second section, I put up queries and visualizations to create some interest. Using the SPARQL template I show the main query of the project, collecting all the entities of the project’s domain. I use Cot and Cob for all subsequent queries so that they don’t take up too much vertical space.
I try to set an interesting defaultView for the queries so that people can visualize the data, but I haven’t used images, screenshots, or interactive charts yet. Those would surely get more attention, but images will go out of date, and I still haven’t learned Vega. Should explore SparqlCharts too.

Properties

While the first two sections are for people visiting your project, the next sections are for those doing the work. The properties section should define all the details you want to add to the entities. If there are too many, you might want to break them down to Core and Extras to ease the workload.
It took me a while to learn and understand the features of List of Properties/Row. Customize the table using description, example-subject, example-property arguments. I used the contextualized-qualifier for the first time in the core properties of the CJI project.

Data table and sub-page

A table of all the entities and properties of the project is useful in doing and monitoring the work. I prefer to keep it on a sub-page as its usually too large for the project page. See Delhi Metro/Stations for an example.
The Wikidata list template gives you a table based on a SPARQL query that gets updated by a bot every day. This has been very helpful for me, I watchlist the page with this table and I get an update if any property of any object that I care about has changed, whether or not it was direct, and whether or not that object itself is on my watchlist. The template also lets you see labels in multiple languages, but unfortunately not descriptions.

Resources, scratchpad & questions

At the end, I have miscellaneous sections to document helpful resources, questions, ideas, or anything else that doesn’t have a place. Often bullet points here become properties to be added, or citations used on the objects.

In the case of WikiProject Delhi Metro, which is the largest WikiProject out of the three I also have a section to help get contributors started, and a userbox too.

For both Delhi Metro and ISRO I have sections for broad topics like launch vehicles or stations, and sections for queries, properties, and resources within them.