I was in my early teens when I chanced upon the whole personality types thing. I immediately scored as an INFP and found the descriptions to be profoundly accurate. It really changed me and made me feel less like a quake.
The best way for me to learn about another type is to meet a person who is that type and get to know them very deeply. I typed my friends and my family, and then random strangers, slowly unraveling the rationale behind my gut judgments. As I understand other types and differentiate different characteristics and hidden motives and a person's dominant objectives and such, I also get to understand my own type better. I like to compare and contrast, back up my gut, I am never completely certain of anything.
At some point three years or so ago, I thought I was INFJ and was very certain of it. With people who are Js, I get very P, as in laid-back, easy-going, very open-minded about planning. But when people who are Ps, I get very J, as in assertive and stubborn about plans and staying with them. People in type forums thought I was INFJ too, until I chatted with a bunch of them and apparently, I take vulgar jokes too well to be an INFJ, and some other stuff too. Haha. And it makes more sense because the relations descriptions works best when I am INFP.
One of the most convincing statements is from socionics where I read that an INFP is what happens when you combine the playfulness of an ISFP with the criticalness of an INTP, which is extremely accurate.
For a brief moment, I thought I could be INTJ because I became very cold, impatient and matter-of-fact with sympathy only for the very, very unfortunate, but I guess that's just another facet of myself. It is what happens when I want to push through my wishy washy crap and focus on what is the most important to me to make up for what I feel very uncertain about. I find pretending to be an INTJ reassuring. I also really, really admire NT traits. For a brief period, I could not for the life of me deal with emotions anymore. Although the type that I'd most rather be is ENTP, but there is no way I am an extrovert and I am a fast thinker, but not that fast.
Being an INFP and an ennegram five helps. I have always scored as an INFP no matter what I took, haha.
Fi explains everything I do. Fe really disturbs me, but my best friends were/are all Fe dominant and I find them, at their best, to be very nurturing and caring and give me the comfort safe I need to express my affection and at their worse, extremely needy and over-dramatic. I find Ti to be an extremely compelling trait and wish I have it. I find Te to be too conventional and practical to be interesting. I still get confused over the difference between Ne and Ni. And I don't have particularly strong feelings toward Si or Se, except that I lack both and it amazes me when boys just fix mechanical things as if it is part of their primal knowledge.