When you have a few minutes to play, go to the RJR Fabrics website, and they have a tool you can use to auto generate color shading. (I've attached a link to it.) This tool can also be used to determine how certain colors/prints might look together. Of course, they use Jinny Beyer's fabric lines as their references, but you will get a real good idea of how your own stash fabrics will look if you select their colors that closest match your own. You can print your results if you want for future reference. It is a lot of fun for any skill level... almost like playing with someone else's stash!!
http://rjrfabrics.com/quilts/atw/rjrgrid.cfm