The build shoud depend on the game you play but it usually don't. If you are lower then Diamond 4 I would suggest a cookie cutter build as in those elos the build paths and unusual builds are not that inportant but the fundamentals are.
For the build I would suggest something like this:
Statikk Shiv
Infinity Edge
Berserker's Greaves with Furor
The Bloodthirster
Lord Dominik's Regards
Def item something like Guardian Angel, Randuin's Omen
I agree, In the sense that the build should correlate with your opponent, but as i'm seeing in my gold 3 elo, that's not the case xD. I would suggest using a site such as
http://www.mobafire.com/ to find a good yasuo build, since this is usually what I use on my top gameplay (Wukong represent). Also, I would suggest using statikk shiv and infinity edge since i've seen 9/10 of my opponents using this item. (excluding a rambunctious yasuo trying AP lol) If you don't want to do any of this stuff, Just try your own thing. Yasuo can do both AD and AP, although AD is a lot better, or in other words, do you mate. Hope this helped!