I, for one, have found much use in MBTI. Since I found out about it a year ago, I've been trying to establish the personality types of people I spend a lot of time with, such as family and friends. And it helps. I feel I can understand them better when knowing their function/attitude preferences. For instance, I could have had my little squabbles with my sister forever, with no idea of what was causing them, had I not come to understand that we're both Judicative - we both make plans and they don't always fit.
Anyway, as to using your personality areas better, I would recommend (to the Introverts, at least)
www.personalitypage.com. In addition to the 16 Portraits, they have a Personal Growth section, where they give suggestions for using one's strengths and managing one's weaknesses. Unfortunately, they haven't yet been able to include suggestions for the Extraverts.
And YES, twoten, typological compatibility has been studied. The "XXXX in Relationships" section of each Portrait on
www.personalitypage.com ends with a suggestion of the two statistically most compatible types for XXXX. The general rules are that you have to have the same dominant function (a generally similar life attitude) and the other characteristics have to be reversed (the two complement eachother in those fields, this seems to be what people unknowingly describe when they say "he/she is my better half"). A slight difference occurs with the 8 types that have a dominant decision function (T/F) - in their case it's preferable that the auxiliary also be shared (S/N), but (a general rule, this one) the type with the "wrong" auxiliary is always the second most compatible, so it's not a big problem if you don't find the _perfect_ match.
I'm an ISTJ too, so I can tell you directly : the most compatible type for us is the ESFP - same dominant (Sensorial) and with everything else inverted. Just think about it ... how adorable is an expressive, outgoing, effervescent Feeler who's also "careless", spontaneous, full of ideas and almost seems to be begging for a J to balance their life ?
I would know, because I've met one (the first one since I've been using these concepts). Right now I'm at the point where I try to find the best approach. I just decided today that I'm going to use our common dominant to get closer to her - the Sensorial function. I'll just do everything I can (in controlled measures, of course) to _show_ her how I fell, to _do_ things that make it clear, rather than say anything. It's typical of us Sensorials to try to convey affection through deeds, rather than words, and who better to be at the receiving end than another Sensorial ?
Anyway, hope this helps. And don't forget : we're not just our types, we're unique, distinct individuals ...
Adi