They also sell flat four trailer wire in rolls instead of running 4 seperate wires.
While individual wires are definitely not the way to go, I don't have much good to say about the flat four ribbon-style wiring either. It has no outer sheath, and the insulation on the individual conductors is extremely brittle in the cold. I've
never seen a trailer in this part of the country that's more than a few months old, that doesn't have cracking in the flat four wiring. A post above mentioned extension cord, and I've used them as well. I've picked up the blue Polar-rated cords and just lopped the ends off. It's easier to fish through a frame than the ribbon cable is, it has a sheath over the individual conductors, it doesn't crack in the cold as easily when flexed, etc.
As far as "good" trailer wiring techniques goes, I'd say the best plan of action is to look at what's been done to preserve reliable wiring and connections elsewhere. You won't see exposed butt-splices or scotchlocks on a vehicle's wiring harness for example. You also won't see a vehicle's wiring harness run along the underside of the vehicle and staple-gunned in place to "secure" it.
I don't think there's any "trick" to good wiring at all, the techniques and components are both well-known and easy to obtain and follow. Many trailer manufacturers have just chosen to squeak by with the bare minimum as far as component quality goes, and then done the install as if the electrics were an afterthought or something....