ISSUE NO. 1
Double check your seam allowance. You might think you are sewing with a 1/4" seam but slight differences can be a big deal.
HOW TO CHECK YOUR SEAM ALLOWANCE
If you're new to quilting, I recommend that you purchase a seam gauge. You can use it to find the exact setting on your machine to give you a scant 1/4" seam allowance.
Move the iron up and down
Do not move your iron side to side as you press. Instead, pick it up and move it as you move along the seam. Moving the iron from side to side can distort your fabric.
WHAT IS A DESIGN WALL?
A design wall is just a blank space to used to lay out quilt blocks before they are sewn together. You can purchase inexpensive vinyl design walls online.
Most design walls hang from grommets and have a layer of flannel on the front. Your fabric will "stick" to the wall allowing you to test your design without pins before the quilt is sewn together.