I managed to reach 500 stones on one char.
Right now I have 462, I sometimes level up some 20+ but family-stones are priorities.
Sometimes opportunities are not expected and kind of subtle.
Once I asked on chat for something related to the garrison -- a trader quest or enchanter's font, it doesn't matter.
A person invited me and I visited them. I noticed that they had a pet wandering around -- a lvl 1 Teroclaw Hatchling.
So while I was giving them thanks for the invitation, I proposed to exchange their 1 lvl Tero for my 25 lvl one, explaining that I can level pets with no effort.
They wanted to refuse, thinking that I'm too generous, but then accepted the offer.