The best tools to use when preparing fabric shapes are templates, I use Marti Michell templates for all my projects.
TEMPLATES
Templates have a set size so knowing if a block is a 3, 4, 5 or 6 patch will determine the size of the block.
(click on image to download)
NOTIONS
No quilt can be made without the use of notions, here is a list of the ones I use every time I make quilt. A few pages were added to write your own list.