What works best for me is..just opening up, and choosing something I am drawn to.
I open my mind, my heart...and then I just allow the stones to come to me.
Sometimes I choose because of shape, or color...sometimes it's how a stone reflects light, or how good it feels in my hand.
And every time I do this...I always subconciously pick the right stone for me at the time I need it!
Try it! It's a lot of fun! Go to a place where there is a lot to choose from, and ignore the names, and supposed attributes...and just go for it!
you will end up with something wonderful meant just for you!