docs: add contribution guidelines

Author: xudafeng

CONTRIBUTING.md

@@ -0,0 +1,45 @@
+# Contributing
+
+Thanks for helping improve Awesome OPC.
+
+## What to Add
+
+Good additions should be useful to people building or running one-person companies, solo founder businesses, indie products, or intentionally tiny operations.
+
+Preferred resources include:
+
+- Official policy, registration, tax, and legal references.
+- Practical tools that help one person build, sell, support, finance, or operate a company.
+- Public case studies, interviews, talks, or products with clear evidence that one person built or ran the business.
+- Books, courses, podcasts, reports, and communities with direct value for solo operators.
+
+## Quality Bar
+
+Before opening a PR, check that the resource:
+
+- Has a working public URL.
+- Fits the section where you are adding it.
+- Is not primarily a low-context advertisement.
+- Includes a concise explanation of why it helps one-person companies.
+- Uses a year for time-sensitive claims when possible, such as revenue, users, valuation, policy status, or report date.
+
+For legal, tax, and policy resources, prefer official government or regulator sources. If you add a secondary analysis, make sure it is clearly labeled as interpretation.
+
+## Format
+
+Use the existing list style:
+
+```md
+- [Name](https://example.com/) — Short factual description.
+```
+
+For tool entries with favicons, follow the existing README pattern and replace the domain, name, URL, and description.
+
+Keep descriptions to one sentence. Avoid hype, unsupported superlatives, and keyword-stuffed copy.
+
+## Pull Requests
+
+- Keep each PR focused on one theme or section.
+- Add new items in the most relevant category.
+- Do not remove existing resources without explaining why.
+- If you are affiliated with a resource, say so in the PR description.

README.md

@@ -18,6 +18,7 @@ Help solo founders find direction, build faster, and thrive independently.
 
 - [Introduction](#introduction)
 - [What is OPC?](#what-is-opc)
+- [Selection Criteria](#selection-criteria)
 - [🎯 OPC Starter](#-opc-starter)
 - [🏛 Policies](#-policies)
   - [China](#china)
@@ -54,10 +55,22 @@ Help solo founders find direction, build faster, and thrive independently.
 
 This project curates everything a solo founder needs — from understanding policies and regulations, to finding inspiration from those who've walked the path, to discovering the best tools and resources that make running a one-person company not just possible, but powerful.
 
-## What is OPC?
+## What is OPC
 
 **OPC (One Person Company)** is a business structure where a single individual operates as both the sole shareholder and director. With the rise of AI, no-code tools, and the creator economy, running a profitable company solo has never been more achievable.
 
+In this list, OPC is used broadly: it includes formal one-person company structures, solo founder businesses, indie products, and small operations intentionally run by one person.
+
+## Selection Criteria
+
+To keep this list useful and trustworthy:
+
+- Prefer official sources for policies, registration, tax, and legal information.
+- Include tools that are broadly useful to solo operators, not just newly launched or promotional products.
+- Add case studies only when there is a public source for the founder, product, or reported milestone.
+- Mark time-sensitive claims, such as revenue, user count, policy status, or market reports, with a year when possible.
+- Keep descriptions concise, factual, and focused on why the resource helps one-person companies.
+
 ---
 
 ## 🎯 OPC Starter
@@ -252,10 +265,8 @@ This project curates everything a solo founder needs — from understanding poli
 
 ## Contributing
 
-Contributions are welcome! Please read the [contribution guidelines](CONTRIBUTING.md) first. Feel free to submit a PR or open an issue.
+Contributions are welcome. Please read the [contribution guidelines](CONTRIBUTING.md) before submitting a PR or opening an issue.
 
 ## License
 
-[![CC0](https://licensebuttons.net/p/zero/1.0/88x31.png)](https://creativecommons.org/publicdomain/zero/1.0/)
-
 This project is licensed under [MIT](LICENSE).