Prepare your work area, lay the flat back stones out face up on a plate rather than on the table.
I use a cocktail stick with a small piece of white tack wrapped around the end to lift the stones and have a few ready for later, as the glue after a while will make it less tacky.
I also have a few cosmetic cotton buds (the pointy end ones or trim a normal one to a small point) ready to mop up any excess glue that leeks from under the stone.
Then get comfortable, as sticking these little suckers on takes hours, It takes me around ten hours to do one shoe!
I tend to start on the heel first at the base and work around and up the heel from the inside to the outer edge as I get further up.
I tend to do a few lines of stones on one shoe and then do a few lines on the other, just so they match in the end.
I found after doing one complete shoe for hours, its harder to remember where you started the first time with the other shoe and more difficult to get them to look even.