theres no one definitive guide yet, they are posted in bits and pieces all over the place for now, plus theres ones that people somehow know to add into them that don;t exist, for example i couldnt stand how grass swayed like it was constantly being blown around, so someone showed me a line to add to tweak how much the grass sways.
try that ini i posted above. i have an i5 2500k and a gtx 560ti. that ini is the absolute best mix of quality and performance, no jagged shadows or anything. I have AA off though because im forcing it through nvidia inspector (get it if you dont already and set it to how I have it int he pic below) and I'm also forcing on ambient occlusion which eats up a load of FPS but worth it if it means i have to keep AA on low. Fxaa is nice to soften the pixelated look at mid and long range, looks more real with it on.
After pasting this ini , don't use the launcher or it will rewrite some things. And remember you have to set your resolution in there manually and paste your GPU's name in there as it appears in device manager (replace my 560 ti)
http://i.imgur.com/Bq2Ty.png