I also use the no pin method that is shown in auntpigglylpn's first video. Fabric placement, short stitches, tweezers.
As in the video, I use a die cutter to cut the pieces. If they are not cut accurately, you will be fighting the pieceing even more. If you don't have access to a die cutter, I would recommend the Marti Michell templates. She has designed the templates for BOTH pieces to be cut using an 'outie' curve. Much easier than trying to get your cutter into that innie. Cut curves using the small 28mm rotary cutter. I know you asked about sewing them, but if they are not cut correctly to start, they won't sew together well.