Im embarking on my first contact prints from 10x8 negative.

I need some help or advice on how to get crisp edges on the final print, what material to use to achieve this.

Im using plate glass quite thick to sandwich the neg and paper confusedwhich is a little over 10x8 should I get some other glass cut at a larger size and what should the approx dims be.

Any help as always will be gratefully recieved

rgds
Dustym