I've been watching video tutorials and doing some Googling, but I just haven't been able figure out exactly how you're supposed to rendezvous with a ship in orbit. I always either end up somewhere in its orbit where it absolutely isn't, or in an orbit with terrible intercepts but no idea how to fix it.
As a concrete example: how would you dock with a ship in a circular orbit up at 250 KM? What would your aphelion and perihelion be at every stage? And most importantly, when you mess up completely, how do you fix it?