Originally Posted by feline fanatic

Y seams are nothing to be afraid of or to avoid. As with any, technique it does take a bit of practice but once mastered they are an invaluable tool in your quilting repertoire, especially for doing mitered borders and classic patterns like Lone Star, Lemoine Star, Attic windows and Tumbling blocks. Also to do many of the fabulous patterns by Judy Niemeyer of Quiltworx

Edyta Sitar has great step by step instructions for doing a Y seam (AKA set in seam) in her book Scrappy Firework quilts. http://www.amazon.com/Scrappy-Firewo...ds=edyta+sitar

She also has a You Tube video
https://www.youtube.com/watch?v=-DBztmnqK-M

If you don't want to spring for the book one trick I used until I got adept at them was to mark the start stop dot on my units so I didn't stitch into my seam allowance. This helped me a lot. The other trick was I made a queen size Tumbling Blocks quilt with Y seams. After doing that many I got quite good at them. And now they don't intimidate me at all.