The density of the embroidery pattern and the content of your fabric you are using for the design dictates the stabilizer needed to make the block. First I will say, there are whole books written on the subject. There are many questions you must ask depending on the way you will be making your blocks. Will they be a quilt as you go though all three layers while embroidering? A appliqued and embroidered block and then set into a top? Or just outline embroidery blocks you make, then made into a top and then quilted. If the latter I would suggest a cut away leave in to stabilize the individual blocks. Then the type of quilting you expect to do while completing the quilt. I like to do an image outline, echo that and then a background fill to my embroidery quilts.