Are you using a hoop? I find it easier to quilt with a lap hoop, as it helps my stitches be more even than if I try to quilt without a hoop. If using a hoop, a common beginner mistake is to hoop the quilt drum tight. You want about a fist-size "give" in the center of the hoop to allow you to manipulate the quilt sandwich as well as the needle.
There are Youtube videos on how to make a quilter's knot, and also how to knot and "pop" the knot into the sandwich at the end of a line of quilting. Just do a search on "quilter's knot", "hand quilting", etc. at the Youtube website.