Loosening the pressure on the presser fot is a must for FMQ,dropping the feed dogs and wearing gloves with little rubber nubs on them and using a darning foot. I don't do SID, can't stay in the ditch, I run a line of straight stitches about 1/4" - 3/8" from the ditch, I run the walking foot along the ditch and that makes for a straighter line. I usually always do FMQ and use high loft polyester batting, but, then I have only machine quilted 40 quilts and only a couple of them were baby quilts all the others were mainly double - queen size.
This topic has been talked about lots of times before and all has been said and resaid.