To successfully determine the socionic type, it is enough to observe three rules and acquire patience. These rules apply to self-typing and typing of other people.
Rule 1. Observation
Observe your reactions and actions in different life situations. Observation must be impartial and objective, without preconceptions and interpretations.
When observing, note: And so on.
Observation should be direct, online. Observation should not be confused with the idea of how you would behave in certain situations. Observation is carried out directly in the process of life, when you do something, communicate with someone, react to something. Only then will it be less subjective.
Rule 2. Comparison
For accurate typing, it is necessary to compare people in the same situations. It may seem to you that you are doing well with logic: you know a lot, pour facts and argue your opinion. However, don't jump to conclusions. Compare how the same thing (volume and quality of knowledge, presentation of facts, argumentation of opinion) happens in other people in similar situations. It is advisable to compare yourself not with one person, but with several, with different people.
Comparison is necessary to distinguish between weak and strong functions. It may seem to you that some function works well for you. But if this function is weak in your sociotype, then your ideas of good and bad manifestations of it are wrong. Comparison is needed.
The more you compare, the more objective your judgments about the work of your socionic functions become.
Rule 3. Exact ideas about the essence of socionic functions
This is the hardest rule to follow. But it's the most important thing. To observe yourself from the standpoint of socionics and compare yourself with other people, you need to clearly understand what exactly you are watching and by what criteria you are comparing.
It is necessary to have an idea as close to reality as possible about what sensing and intuition, logic and ethics in socionics are. How extraverted and introverted functions manifest themselves, which are in different positions in the structure of the socionic type. If your theoretical ideas are "lame", then the chances of making a correct socionic observation and correct socionic comparison are reduced (not reduced to zero, no, but significantly reduced).
Conclusion
To correctly determine the socionic type, in addition to observing the described rules, it is necessary to add patience. "If you hurry, you will make people laugh." Avoid hasty typing, it is wrong in most cases. It takes time to gather enough facts through observation and comparison. The wider the range of situations in which you observe your own and others' socionic manifestations, the higher the likelihood of an accurate determination of the sociotype.
Good luck with typing and self-typing. And finally, let me remind you: it is better not to define the sociotype at all than to define it incorrectly.