Question: If I choose to wear a medical mask, what should I keep in mind?

Answer passage (source: WHO):
page_title: Q&A: Masks and COVID-19
section_headers: Does WHO recommend the use of non-medical masks in the community?
section_content: Currently there is not enough evidence for or against the use of masks
(medical or other) for healthy individuals in the wider community. WHO
continues to recommend that medical masks be worn by individuals who are sick
or those caring for them. WHO is actively studying the rapidly evolving
science on masks and continuously updates its guidance.
In the interim, to support countries in their decision-making process WHO has
provided advice through a risk-based approach for the use of masks in the
context of COVID-19.

Reviewer feedback on this answer:
The question is about what to keep in mind when wearing a mask not whether to wear a mask or not. (as an aside, I'm fairly certain this answer is out dated.)
This question does not answer what people should keep in mind about wearing masks.

Reviewer ratings:
Could be Improved
Bad

Answer passage (source: WHO):
page_title: Q&A on coronaviruses (COVID-19)
section_headers: How to properly wear a medical mask?
section_content: If you choose to wear a mask:

Before touching the mask, clean hands with an alcohol-based hand rub or soap and water
Take the mask and inspect it for tears or holes.
Orient which side is the top side (where the metal strip is).
Ensure the proper side of the mask faces outwards (the coloured side).
Place the mask to your face. Pinch the metal strip or stiff edge of the mask so it moulds to the shape of your nose.
Pull down the mask’s bottom so it covers your mouth and your chin.
Do not touch the mask while you are wearing it for protection.
After use, take off the mask with clean hands; remove the elastic loops from behind the ears while keeping the mask away from your face and clothes, to avoid touching potentially contaminated surfaces of the mask. 
Discard the mask in a closed bin immediately after use. Do not reuse the mask.
Perform hand hygiene after touching or discarding the mask – Use alcohol-based hand rub or, if visibly soiled, wash your hands with soap and water.

Be aware that there is a global shortage of medical masks (both surgical masks
and N95 masks). These should be reserved as much as possible for health care
workers.
Remember that masks are not a substitute for other, more effective ways to
protect yourself and others against COVID-19 such as frequently washing your
hands, covering your cough with the bend of elbow or tissue and maintain a
distance of at least 1 meter from others. See basic protective measures
against the new coronavirus for more
information.
Follow the advice of your national health authority on the use of masks.

Reviewer feedback on this answer:
Provides solid information about considerations when wearing a mask. It's on topic and thorough.
The answer provided has an almost exhaustive list of things to keep in mind when wearing a mask, which is what the original question is asking.

Reviewer ratings:
Excellent
Excellent

Answer passage (source: WHO):
page_title: Q&A: Masks and COVID-19
section_headers: What individuals should wear medical masks to prevent the spread of COVID-19 according to WHO?
section_content: Medical masks are recommended in health care settings. However, it is
important to remember that the use of masks should be combined with other key
infection prevention and control measures such as hand hygiene and physical
distancing, as they do not serve all purposes to protect against COVID-19.
WHO recommends the use of medical masks for the following individuals:
Healthcare workers
Why? Medical masks and respirators such as N95, FFP2 or equivalent are
recommended for and should be reserved for, healthcare workers while giving
care to patients. Healthcare workers are the most exposed because they are in
close contact with people with suspected or confirmed COVID-19 and their
surrounding environment, which are the main routes of transmission.
People who are sick and exhibiting symptoms of COVID-19
Why? Anyone who is sick, even with mild symptoms such as muscle aches,
slight cough, sore throat or fatigue, should isolate at home and use a medical
mask as much as possible according to WHO’s recommendation on home care of
patients with suspected COVID-19. Coughing, sneezing or talking can generate
droplets that can spread the infection. These droplets can reach the face of
others nearby or land on the surrounding environment. If an infected person
coughs, sneezes, or talks wearing a medical mask, this helps to protect those
nearby from infection.
Anyone taking care of a person at home who is sick with COVID-19
Why? Those caring for individuals who are sick with COVID-19 should wear a
medical mask for protection. Close and frequent contact with someone with
COVID-19 can put those caring for them at high risk. National decision makers
may also choose to recommend medical mask use for certain individuals using a
risk-based approach. This approach takes into consideration the purpose of the
mask, risk of exposure and vulnerability of the wearer, the setting and
feasibility of use and the types of masks considered.
See “Advice on the use of masks in the context of COVID-19”.
WHO will continue to update guidance according to scientific findings.

Reviewer feedback on this answer:
The question is about what to consider when wearing a mask, not who should wear one.
This answer does not relate to what people should keep in mind about wearing a mask.

Reviewer ratings:
Bad
Bad