When building an app, collect only the personal information the business needs, get a guardian's consent for children under 14, and write the privacy policy clearly

Moderate value
Evidence B
Keeps you free
Free
Takes minutes
Some willpower

In plain words

Collect only the information the business needs, and get a guardian's consent for anyone under 14. Violators are first ordered to correct it, and the app may be taken down. For refusing to correct, the fine is up to 1,000,000 (100万) CNY, and the person in charge is fined 10,000 to 100,000 CNY. In serious cases the fine is up to 50,000,000 (5000万) CNY or 5% of the previous year's turnover, and the person in charge is fined 100,000 to 1,000,000 CNY. People who write code and build the product can also count as the person in charge.

Cost: Free. Before launch, check the app's list of requested permissions and its privacy policy against each other, and drop any permission you can do without. The hard part is that the product side always wants to keep some data that "might come in handy later."
What you get: Handling personal information requires a clear and reasonable purpose, directly related to that purpose, and done in the way that affects individual rights the least. Handling personal information requires the individual's consent or another lawful basis. For anyone under 14, the consent of a parent or guardian is required. For violations, the regulator orders correction, gives a warning, confiscates illegal gains, and orders the offending app to suspend or stop providing services. For refusing to correct, the fine is up to 1,000,000 (100万) CNY, and the directly responsible managers and other directly responsible personnel are fined 10,000 to 100,000 CNY. In serious circumstances the fine is up to 50,000,000 (5000万) CNY, or up to 5% of the previous year's turnover. The responsible persons are fined 100,000 to 1,000,000 CNY. These people may also be barred for a set period from serving as a director, supervisor or senior manager of a related company. For selling or providing personal information in a way that amounts to a crime, see §11.4 (nationwide)
Notes: In practice, "directly responsible personnel" often turns out to be the people who write code and build the product. The Ministry of Industry and Information Technology regularly announces apps removed for violations, but this guide could not verify which announcement, so it does not cite one.
Evidence grade: B : Supported by research but without a precise number, or based on small or single studies.
Sources: 全国人大常委会 (2021). 个人信息保护法（第六、十三、三十一、六十六条）. http://www.npc.gov.cn/npc/c2/c30834/202108/t20210820_313088.html

Translated from the Chinese original. Original book, section 11, tip 15. This section describes legal rules, mostly mainland China’s. It is general information, not legal advice; for your own case, talk to a lawyer. Content may be out of date and rules differ by place. When you actually deal with an agency, a doctor or a court, follow what local officials, doctors and lawyers tell you. Disclaimer