Here is a brief summary of Model A and the socionics functions:
Te: is about practicality, efficiency, empirical logic, factual information, etc. Therefore, is about logic. However, unlike , is concerned not with an elegant, speculative, or valid solution on purely theoretical grounds, but a logical solution that "works." In this sense, the nature of is practical logic.
Ti: is about analysis, clarity, logical relationships, systematic thinking, etc. Consider a mathematical formula. I would argue that understanding a mathematical formula is a matter of Ti. The reason is that a mathematical formula is a clear, concise specification that requires an understanding of the logical relationships amongst its parts. The formula might describe something in the real world, but trying to understand it is a matter of pure logic (it could be a manifestation of Te if understanding the formula is serving some kind of practical purpose, but that's a separate issue).
Ni: is about forecasting, having long range vision, thinking in the future, daydreaming, having an idiosyncratic world view, appreciating the meaningful and "deep", etc. There are really two aspects to Ni. The first has to do with time. In this sense, people who use like to live in the past and/or future. The other aspect of Ni has to do with having a deep or poetic nature. For example, INFps (and INTps to a lesser extent) might express this through a preference for some type of spirituality.
Ne: is about seeing possibilities, novelty, ingenuity, inventiveness, seeing the "big picture", seeing and developing the potential in yourself and others, etc. Like , there can be two aspects to . The first is essentially about generating ideas. Many Ne types like to speculate about what is possible more than what is actually the case, and this can take the form of generating ideas. Also, when one has to show ingenuity they usually do so through some sort of creative idea, and this would be an expression of . The other expression of Ne is being able to see the potential in situations, people, etc. This means that Ne types are able to help people develop their potential. (it also helps them to find situations that have potential).
Fi: is about sentimentality, moral sensitivity, integrity, and depth of feeling. In this sense, there are two types of . The first is about moral integrity, the second is about having deep, hidden emotions. (I suppose another illustration of Fi is having a good understanding of human relations. For example, Fi types are very good at choosing friends and forming deep bonds with others.)
Fe: is about emotional expression, enthusiasm, excitement, etc. Really, Fe involves all of the external manifestations of emotions. Therefore, Fe types are really good at being able to sense the moods and emotions of others, and by the same token, they are able to act in such a way as to elevate other people's moods.
Si: is about comfort, aesthetics, being in touch with your senses and your body, etc. Really, is about anything sensory. types are really good at noticing things that involve their senses, whether it be art, their state of health, their environment, etc. Also, Si egos are able to create enjoyable sensory experiences, such as good food, a comfortable environment, etc.
Se: is about strength, power, self-confidence, status, etc. Basically, view themselves as having a strong sense of reality, and, as such, they aren't afraid to tell others what they think. They usually have strong personalities, and are capable of getting others to accomplish what they want.
Now that we've seen the nature of the functions, here is how they would fit into one's psyche based on Model A:
Ego: functions that you value, are talented in, and are confident in.
Super-Ego: functions that you are weak in and dislike in others.
Super-Id: functions that you are weak in and like in others.
Id: functions that you could be strong in but basically ignore and that you dislike in others.
Functions 1, 4, 5, and 7, are more pronounced (i.e., they fit the descriptions of each block more than functions 2, 3, 6, and 8).
If you can't tell what functions you value, then take a look at this vocabulary project: Vocabulary - Wikisocion.
How you "feel" about the expressions of the functions might give you some insight into how they work for your type.