Introverts and J-P Preference
In MBTI theory, IxxPs are dominant judging types while IxxJs are dominant perceiving types. This can cause a lot of confusion. Judging versus perceiving is not a debate between whether someone is organized or not. It determines which of your top two functions is extroverted. For introverts, this is always the auxiliary function, and not the dominant, and so an IxxP can appear more adaptable and an IxxJ more structured, but underneath that outer shell, IxxJs can be quite adaptable and IxxPs can be very structured.
Male Fs and Female Ts
It does seem that when I skim the "what's my type" forum, most people like to guess men as Ts and women as Fs. Sometimes, even the poster is quite certain and later discovers they may have been wrong. There are plenty of male Fs and female Ts, however. Although it probably IS most common for a woman to be a feeler and a man to be a thinker, it is not always the case and male feelers will still use their thinking function more than a female of their same type, and vice versa for a female thinker.
HSP and Other Psychological Contributions
HSP is one of the reasons I originally mistyped myself. I was absolutely certain I was an INFJ for months, until I realized that I really couldn't possibly be an auxiliary feeler. I just thought I was because I can't help but cry at things normal people don't cry at, and I feel stuff so strongly, etc. Anyway, HSP is the only one of these I know well, but it makes one very sensitive to stimuli, and in turn, sensitive in general. Ts can be strongly moved by this and thus mistype themselves as Fs, or confuse themselves in regards to their sensing functions, which can be affected by HSP (typically, both Se and Si appear to be heightened). Sometimes, HSP can also make an extrovert believe they might be introverted.
Liking People and Extroversion
Just because you like people doesn't make you an extrovert. Introverts can like people just as much as extroverts. We just can't handle as many of them. Also, extroverts can very much dislike people.
Liking People and F-ness
Just because you like people doesn't make you an F. T types can love people too. I love people. I just don't want them around me all the time, and my emotional approach to them is admittedly shallower than a feeler's would be. Meanwhile, plenty of Fs can also dislike people if they have lost their ability to trust them.
Introverted Perceiving Functions and Perceiving Types
Introverted functions (Si and Ni) are difficult to define, and can sometimes be confused with other things. For example, I as an INTP might relate to Ni and Si, because I am an intuitive type, and because I use Si. An ESFP might feel like they related to both as well, because they would use Ni and because they are a sensing type (though it is thankfully more difficult to confuse Se and Si than Ne and Ni).
Every type can get stuck in a loop using their dominant and tertiary functions, and skipping their auxiliary. I'll label each loop:
INTP - Ti/Si
INTJ - Ni/Fi
INFP - Fi/Si
INFJ - Ni/Ti
ISTP - Ti/Ni
ISTJ - Si/Fi
ISFP - Fi/Ni
ISFJ - Si/Ti
ENTP - Ne/Fe
ENTJ - Te/Se
ENFP - Ne/Te
ENFJ - Fe/Se
ESTP - Se/Fe
ESTJ - Te/Ne
ESFP - Se/Te
ESFJ - Fe/Ne
So take an ENFP, for example. Their loop is Ne/Te. An ENFP stuck in a loop might appear very similar to an ENTP overall, however if one pays attention to their functions, it should become clear if the ENP is using Te or Ti. ENFPs in this loop could be highly abrasive and easy to rile up about emotional topics, but may seem to take more practical approaches to life than what one would expect.
Similarly to Dom-Tert loops, I'm pretty certain someone can seem to fall in an auxiliary-inferior loop. This one is a little different than the dom-tert, because it is difficult particularly for introverts to not notice that they are behaving strangely and out-of-character. Introverts will get tired using their auxiliary and inferior functions so often, and then go home and retreat into their introverted functions.
What is happening here, usually, is usually an introvert attempting to be an extrovert. I'm not sure how/if this happens with extroverts yet, but I'm sure it can. I have yet to see an example, however, so I'm going to use myself. I am an INTP, however in high school, someone might have thought I was an ESFJ or maybe an ENTP. I appeared to use far more Ne/Fe than I actually feel equipped to use, and then came home and dwelt in my Ti/Si for the rest of the day (which my mom hated, hah). This loop is less common, but it can occur, especially in teen years when someone is still developing and experimenting with their weaker functions.
Some types may be heavily influenced by the other types around them. For example, someone else I once knew was also an INTP, however she and I are quite different. She is the only strong Ti user in her family, and therefore has a very Te sense of humor. I, on the other hand, was raised by an ISFJ father and had strong ENTP influences in my mother and brother. This provided a stronger preference for Ne and Fe than other INTPs might have. I still enjoy Te humor although my family doesn't, but there is no doubt in me that my Fe especially, was affected by my family.
Also, because I was so encouraged by my mom and brother to get out and be friendly with people, I did so (and over-exhausted myself in the process) and now many of my past high school friends are left with a very extroverted, airheaded, and friendly image of me.
People fail to realize that ENTPs, for example, CAN plan, even if they are not always inclined to. My mom makes plans all the time, and they are usually very detailed. She rarely follows through, but she DOES plan. Furthermore, an ENTP might be raised to need to plan, and thus have skills that would appear just as natural on them as on an ENTJ.
ISs and Extroversion versus Introversion
ISs are often mistaken for extroverts by others, because ISPs like to get out and do stuff, and ISJs can be very outspoken (ISTJ) or very social (ISFJ). Not all introverts like staying at home or doing quiet brain things like us INs.
SJs and Imagination or Quirkiness
I remember early on, reading descriptions of SJs and thinking how dull they all sounded. But then I found them in real life, and I've discovered that SJs are actually quite quirky and often very imaginative. My father exhibits a punny humor that can be attributed at least partly to Ne. Another SJ I know collects socks and scarves, and writes stories with some of the most entertaining premises I've ever heard, and another friend makes jewelry, cooks, acts, and writes creatively. They are always described to be practical, but I would revise that to say that they are simply more concerned with the here and now, physical and/or present concerns.
ENs and Extroversion versus Introversion
Almost every EN I know has thought they were an introvert at one time or another. Especially ENTs. This is probably because the stereotypical extrovert is an ES. ENTPs are particularly easy to drain, as their dominant function (Ne) is very cerebral, rather than physically active, and Ti finds humans inefficient and in the way. ENTPs who mistype themselves as introverts often mistake INTPs as broken versions of themselves, who simply never learned to socialize. But, if ENTPs are so quickly drained by social interaction, I'm sure you can imagine INTPs are even more so. ENTJs are also rather prone to believing themselves to be introverted, as well as some ENFPs. I haven't met as many ENFJs like this, though I think ENDJs are easy to mistake for introverts looking in from outside.
S-types, F-types and Intelligence
It should go without saying, but this kind of discrimination still happens on a subconscious level, I think. I've known many ST programmers (I think programming actually bores a lot of NTPs) and every SF in my life is well-spoken. Many are actually very intellectual. In fact, my grandfather is an ESFJ and my husband an ENTJ. My grandfather reads much, much more.
And many a feeler will passionately assure you using lovely words that they are indeed very smart. If you are trying to type someone you know to be intelligent, don't immediately shun the idea that they might be an S or an F.
Thinkers and Creativity
People tend to be mistaken in thinking that if you are creative, you must be a feeler because you put emotion into your work. This is by no means true, and I'm pretty sure anyone who consciously thinks about it comes to the same conclusion. Many famous artists have been thinkers. I'd like to take a moment to brag that INTPs make up a large number of famous creative peoples. I also know other T-type individuals that are quite creative - INTJs, ISTJs, other INTPs, ISTPs, ENTPs.... pretty much any T-type has the capacity. These people write stories, make jewelry, decorate food, make music, and everything else.
So if you're having difficulty typing yourself or someone else, or are second-guessing someone's type, hopefully this should help you pick things apart.