I'm starting to print bigger.

Started from 8x10 and now I am printing 11x14 more. In a week or so, I will be printing 16x20, I hope.

Here's a question for those who have experiences in printing big. How do you minimize waste in paper? I can print 8x10 and get adjustment and contrast right, but when I scale up to 11x14, pure mathematical calculation doesn't do it. Contrast looks different and the overall impression of the print isn't the same - beyond the size difference. I find I need to bump up the contrast 1/4 grade or so, and lighten the print slightly to get the "same" print. I'm expecting, by going to 16x20, the difference will be greater.

In short, I can practice on 8x10 but I will have to go through few trials on 16x20 as well.

Are there any tricks and tips on minimizing waste on large (and expensive) paper?

To start, I'm going to use Pearl RC paper.