Some of my quilts have puckers and crooked lines and I just try not to fret it. I will never be able to afford to have a long arm or pay someone to do it so I just live with the imperfections.
I have learned that a lot of it lies in the sandwiching. You must be sure to get that backing flat and pin often.
My solution is to only make lap size quilts and they are almost too big for me to quilt.
Good luck!