What's the best/safest way to walk from entire lenght of europe to entire lenght of asia?

I have for a long time dreamt and planning for go for a trip from Sweden to South Korea and want to get there as safe as possible, at the same time I would want to avoid cold areas like Siberia if possible and to see interesting places on my way, I don't want it to be too hot neither so I gonna start the journey in August according to plans