As mentioned in the very first photo post, here's an example IMHO, where less would have been more. I should have left off every other one of the red/white markings on the bottom and sides of the car. This is a MARX solid door type box car.
This next photo is one of three of the very first repaints I attempted. This now has to be about 30 years old. These were Woodland Scenic brand dry transfers. Initially I'd seen so many poorly done decal jobs, that I was only going to use dry transfers. Until I realized some decals are better than others, and there's also a right and wrong way to do them.
This has to be the most ambitious of all the self-made decals I ever did. The car started off as a screw up I made when trying to minimally alter a Lionel car. Now with two bobbing giraffes on each end.
Referencing the first photo here, I think less works better. I didn't use as many of the red/white safety markings. This one is a 5000-series K-Line box car.
I've long known what Menard's has recently figured out: That painted door guides look much better. Though they are a bit of a pain in that they are more prone to chipping of paint, and when you push the rivets back in to secure the door guides, I inevitably lose some paint and have to do some touch up.
And also here's a good example of compromise: The NS logo is an HO scale Microscale locomotive decal. Still, a little small for a box car, so I leave on the "Norfolk Southern" words, even though prototypically, they shouldn't be there. But all the other traditionally sized NS box car offerings have all been BLACK painted box cars, also not correct. So color-wise, I'm one up.
I remember when OGR Magazine reviewed the traditional 027 NH passenger cars from the mid-1990's, they concluded the New Haven lettering on those was too large for the car.
I agree, so I redid mine.
Visually, I like the Penn Central. PC was never offered on a traditional 027 passenger car, so I took care of that. As with the New Haven above, I actually go to the trouble of painting the molded in car diaphragms black. A very steady hand is required along with some patience.