Aside from inclines, you really need a low bodyfat to get that nice ripped line going from your middle chest up to the neck area. Otherwise, forget it.
I'm not joking. There are a greater number of receptors in the shoulder girdle area which is why the upper chest, traps, and delts can look "steroidal."
There is some argument about whether different parts of the chest can be 'emphasized' since it is just one muscle. Assuming differnet parts can (upper/lower/middle), declines would focus on the lower, not uppper, part of the pectoral.
I second those who say that the chizzle-foshizzle comes from low BF less than muscles. Given that you are a female, obtaining lower BF might also result in a shrinking of breast size.
MAybe if you posted a pic, we could offer more guidance.