Water spray bottle
A small spray bottle full of water is very useful - a quick mist of your clay will stop it sticking to things such as texture sheets. Don't overdo it though, or you'll end up with a sticky mess.
The jury's out on whether it's better to spray the clay, or the item which threatens to stick.
A light dusting of cornflour works too - especially if you can apply it evenly using a 'pounce'.
The water will dry - eventually - but sufficient quantities of cornflour will change the workability of your clay, so go easy!