Kiwi Farms

What, in your opinion, are the best exercises, number of reps, and number of days per week for an ectomorph to get better (i.e. larger and firmer) pecs?
It is easy enough to find exercises that work the right muscle groups, but I am still trying to figure out the optimal number of rest days and the optimal number of reps.
Does anyone have advice? I am trying to build a more muscular and defined but still relatively slender form.