I don't know about "good" but here are a few for you to look at.

http://www.everythingsewing.net/pillowcase_dress_how_to.htm

http://www.jenleheny.com/pillowcase-dress-instructions

http://www.youtube.com/watch?v=QtuGUB-jsH8

those are really good ones!

There is a new book available titled: Craft Challenge: dozens of ways to repurpose a pillowcase.  By Suzanne Tourtillott. ISBN 9781600594021.  This book has several dress ideas as well as aprons, bags and other cute things. The book is available at the library.

I googled it about a month ago and found a few on-line.  I took  couple of them and put the info together.  The dresses turned out awesome.  good luck.  The biggest is get the messurements.  I know that I used a pillow case that I don't use anymore and made a mock one.  Took the width of the pillow case, added length to it because my girls are older.  I then when on line and too the advise of the arm holes and went to work... they are so cute and was great for the party I made them for.  We all match.