How do I go about studying the middlegame

So I'm just wondering, are you getting any useful ideas out of this thread?

15...Qf6 and he loses the knight.

Gee, I wish I'd thought of that (oh wait...)

Anyway, as usual around here, you go through the trouble of talking about somebody's game in a more than cursory fashion, and then your comments just get ignored in favor of the usual inane generalized blather (not that that's a jab at you, wafflle, as you make a lot of useful--and specific--remarks...but at pretty much everybody else)... 

While browsing these forums, and things online, it almost seems like the middlegame is a myth to most chess players. There seems to be a lot of people that swear upon their openings, and that their openings win them the games. And I guess that makes sense in some ways. But I tend to think the game doesnt literally end until the rooks are at least connected, which to my little knowledge, is the middlegame. And the area which I have the most trouble with.

I know how to finish developing, and how to win/draw an endgame. I have trouble not knowing what to do in the middle. And seems to be where I lose most games. By just flat out hanging a piece while trying to come up with a weak plan off the top of my head, or by sticking myself in a fairly basic(even for me) tactical line that I have no way out of. I dont know how to figure out weaknesses. Finding ONE weak square out of 64 seems insane to me at this point. I do understand that sticking a knight or one of those weak squares though can be a bit of a pain for my opponent.

Alright, all in all Im so lost I dont know how to word this lol. How do I practice/study the middlegame?