Basically practice and exposure to situations that make you uncomfortable, learning to deal with failing without feeling like a failure, once you no longer feel a pressure to act a certain way in order to be able to better deal with you'll ironically probably be better at dealing with people already because you'll be able to act naturally with more confidence. Your Ti can be sharpened by using it in conjunction with Fe, if there's a purpose to what you are doing your Ni will set upon it and that's what you'll need to sharpen Ti, Ti is there to make sense of and sort out the insights provided by Ni, but Ni wont trigger if what you are doing has no appeal to you.
The thing with INFJs like Carl Jung is how they are able to reason logically in ambiguous subjects, they have a natural penchant for metacognitive thinking which I think is unrivaled. This lets them sort out and deal with emotional factors in a logical fashion like none other. It makes them capable psychologists, philosophers, linguists, anthropologians and even politician. But they don't match up to NT's in more detached subjects.
Plato, another likely INFJ, can be seen as an important precursor to Jung, his world of ideas matching Jungs collective unconscious. Yet it is the theory of evolution, a product of the INTP Charles Darwin that provided it with an origin. With Plato it was divine, Jung thought it could be either divine or natural, Darwin's theory neatly provided a means of discarding the divine explanation and in doing so gave Jung's theories greater weight. These are examples to support a general tendency though, it's not like you're limited to these subjects, they are just areas where INFJs typically excel.
Here is a good post on INFJs:
http://www.intpforum.com/showthread.php?t=7016
Notice the quote in the beginning of that post, what Jung says there applies to INFJs more than any other type.
It's also worth saying that I've not really got any idea of what type you are myself because I can't tell from what you've written thus far, and also that a lot of what I wrote are my own conclusions rather than MBTI canon.
Edit: Oh yeah, this shit here was also a problem for me lol:
I guess that sometimes I am random and make strange connections so I thought it was Ne.
I guess that Ni users can do that as well, although in their case I think its more for the effect or for the sake of humor rather than as a means to pursue truth as it is for Ne users. Ni also makes connections after all, they just happen internally rather than externally, when I go into random strange connection sprees it feels like it's weird conceptual mutant babies coming from inside me more than that it's me putting them together before me. Or I dunno. Dinstinguishing between Ne and Ni is fucking hard when it comes to some things.