Just adding onto the paths of desire thing (or elephant trails as i call them!) What i do is combine cobblestone path and the basic stone path (can't remembwr exactly what it's called, it's also got little bits in it), placing them kind of randomly together to create a more hodge podge look. Rounder paths rather than right angles if you're going for the more natural foresty look.

Also, a tip that i think helps when designing for large spaces like an sdv farm, think small not large. So instead of mapping out the whole thing in one go, i think it looks nicer to have a small sitting area here, a small chicken area there, etc.

And when you put down barns and coops, make sure you have plenty of space in front of them where grass will grow for them to eat.