Basic Rose Pruning Rules: 3 "D"s, 3 "T"s, and Balance
I have a lot of time to think when I'm pruning hundreds of roses, so I started thinking about how to boil rose pruning down to a few simple, easy-to-remember rules. This is what I came up with:
THE THREE "D"S
Remove anything Dead, Damaged, or Diseased--for obvious reasons.
THE THREE "T"S
Remove anything Thinner than a pencil (unless the normal healthy mature growth is all thinner than a pencil).
Remove anything very Tired (several years old and no longer productive) (unless very Tired is all you have left).
Take brief notes or photos, so you can remember what you did this year, to help yourself out with pruning next year. Review your photos and notes before you go out and prune. It will help you decide how to proceed. Sometimes you can't see improvement or decline without contrasting it with how the plants looked a few years ago, and who can remember, off the top of their heads, how they pruned last year?
Lastly, balance: balance preservation with stimulation
You want to preserve as much of the plant as you can because roses store energy in their canes. When you cut off cane (stem) you are cutting off stored energy that the rose had planned to use during tough times. So why prune at all, then? For stimulation. Balance out the need to preserve stored energy with the need to stimulate vigorous new growth.
Imagine a rose with a few nice strong canes, pruned back to the same spot on each for several years. (I see roses like this often.) Those canes will age and decline over time. You'll end up with a rose that has a few very old canes and nothing else. Doom. Remove enough to stimulate a new cane or two every year, if you can, but don't overdo it. You can't glue it back on.
It should be noted that some varieties just don't grow very many new canes no matter what you do. They just don't. After a period of time all you can do is dig it out and plant a new one. Its the nature of the beast.
The various details about outward facing buds, angle of cut, the right time to prune, and so on are all helpful, but the rules outlined above I think is the essence of the thing. Now back to the great outdoors. I have a lot more roses left to prune.