I dilute 50-50 with water. You don't have to spread it over the whole thing. Just squirt a thin line 6 to 8 inches apart. Then I smooth that out with my fingers so there are no big globs. The fingers will get washed later. (Sometimes I don't wash them until the whole quilt is finished.)
One time I had the glue too thin and it didn't hold well. Some batts don't hold as well either. I always put pins around the outer edge to keep the pressure off that glued spot until it is sewn. Sometimes I even put the binding on before I quilt the insides. (Horrors!)