Russian forces performed professionally in Crimea and NO ONE get killed. In East of Ukraine it was not russian forces it was bullshit, that is why thousands died.
"No one" got killed because no one resisted(there was ofc. the typical Russian Political murders, but i know this is considered normal where you come from), because the Russian presence there was to great.
This is something that all countries should learn from... Not to give up, but for the love of god don't have a large buildup of Russian troops in your country, at some point they will think it is theirs.
And I think you forget they where not wearing Russian uniforms to start with.