What the Ukrainians need to do, is to step down and not provoke. Putin's motive of placing troops in Ukraine to safeguard the Russian populace there, only retains what shred of credibility it has, if those Russians are actually under threat from Ukrainians. So far, they haven't been - not in the slightest. Putin can't make a first offensive move without probable cause.
Put the pressure on him economically. When Russian business interest start to take hits, criticism of Putin will emerge within Russia and more importantly, within Putin's own inner circle as well.