Unless you have purebred indica or purebred sativa geneticss to work with, you are trying to raise latent expressions through hybrids of unknown/uncertain/mixed genetics. Most commercial breeders have hundreds or thousands of plants they grow, to select a small hand full of those that are showing the expressions they're looking for.

Although you can use selective breeding to 'change' the genetic expressions, there's no guide that say's that you need to cross plant "A" with plant "c", then backcross the results with plant "A" to get more trichomes per square inch, or to get a different medicative effect, or to reduce chances of hermaphrodism...
On a small scale, you will likely be unsucessful at pinpointing, isoating, or encouraging specific latent expressions in offspring. Technically...it's a crap-shoot.

-But-

You can easily use plant maturity to adjust aroma's, flavor's, and medicative effects.