I have a canvas Vango Force 10 tent that's quite old, and 3 nylon tents
With all of them I lay them down lengthways; fold them to a suitable width for the bag, then roll them up, usually tying them first with a couple of lengths of cord.
They're still OK, with no signs of wear, but I try to fold them so I don't always get the fold or crease in the same position
A couple of months ago I bought an MSR Hubba tent, and the fabric is much thinner and more slippery than my nylon tents. I shove this randomly into the bag, as you do with a sleeping bag. Admittedly I've only had the tent a few months, but it doesn't seem to be doing it any harm
Makes it easier to pack up in the morning, too