I always go for thumbs in direction of fingers (suicide grip for bench press). This lets the bar sit lower down my back, just down from the top of my shoulders (hard to explain because I forgot the terms). But having your hands like that pushes the bar into your back giving a lot of grip and a solid purchase on your back. Also it helps in tightening your back and I find it helps put your thoracic arch into extension (I think thats the term for it?).
Our deepest fear is not that we are inadequate. Our deepest fear is that we are powerful beyond measure.
"When in doubt, just get really, really strong. It tends to cure most problems in training – and life." - Wendler