It seems to me that the best faq on this subject that I have read is on zentalk rog5 in Chinese language but I can not find it anymore, maybe a moderator here has a link.
In the meantime, some general advice
1) Screen protection
There are protections that penalize recognition, nothing can improve, it must be changed by a certified fingerprint recognition protection.
You have to scan with the protection if you have one, if you put it in later, remove the fingerprints and start the recognition again. the same if you change or remove it.
The display must be clean
2) Hands and fingers (dryness and wounds are the enemies)
There are people who have very dry or dehydrated hands, the cause must be treated. change soap for example. If the cause is deep, no sebum production, consult a skin specialist.
If you are using a hydroalcoholic lotion because of Covid-19, use another method while the skin is rehydrating. (a few minutes)
A good lotion shouldn't leave your hands too dry, but unfortunately this is not often the case.
Diabetics, if possible avoid using the fingers used for blood sugar measurement.
Do not use an injured finger of course.
3) learning
preferably in natural light, not in direct sunlight or in the dark.
Do not use more fingers than necessary, usually 2 on one hand and 1 or 2 on the other hand (safety if you injure your finger)
take the time, use the pressure you will use for the release, be careful not to slip.
Learn in the positions you will use for unlocking, flat or tilted on the desk, while holding it, on the stand in a vehicle. this matters because the angle and pressure may be different.
To do this, register the finger that is used the most several times as a new fingerprint in each position of use.
Example at home:
Right index finger, 3 learnings, desk support, car support, by holding it with the left hand.
Right thumb, 2 learnings, desk support, holding it.
Left thumb, safety, 1 learning.
Even if you use it only in one situation, by performing two recognitions for the same finger you will certainly get a better success rate.
Don't turn your finger, no 45.60 or even 360 ° (already seen!), Just change a few degrees, tilt and rotate and change the left-right pressure slightly.
4) Recognition
Forget the habits taken with the physical sensors located outside the screen, you will never get the same recognition speed with current technologies of the sensor under the screen, it offers space saving by removing the border or better ergonomics than those located on the back or on the power button but not the speed. Recognition is not as efficient and it is penalized with additional energy management.
In short, if you typed very quickly (<0.1 ") with previous smartphones, you must now adapt
Press (0.2,0.3 ") and test a few different speeds and pressures
If the device has been on standby for a while, tap very quickly to wake it up and then press the sensor.
