When cutting burlap, it helps to pull out one of the strands where you want the cut to be. Then just cut right where the strand was for a nice straight finish.
Make sure to use a heavy duty needle when sewing burlap. Set your machine to a short stitch length so the stitch catches all the fibers and strengthens the seam. To keep the edges even, you may want to use a walking foot or wide presser foot.
Burlap tends to fray a lot, so it helps to use a serger or zigzag stitch along the edges. You may also want to use fray check afterwards.
After sewing burlap, you’ll probably want to wipe down your machine because there will likely be a bunch of loose fibers.