Did a TON of 1" strips. Not all of them were perfect, but it was not bad.
Use a walking foot - it keeps the top fabric from shifting.
If your sewing several together alternate the direction. I always leave the threads at the beginning long and trim the end thread close so I know which end I started at last.
Try a glue stick to match the pieces instead of pins.
Make sure your 1/4" is accurate all the way down. Lay it on your cutting mat to make sure it's still straight edge to edge. Measure the seam with your ruler to make sure the 1/4" is in the same place all the way down.
When you iron it make sure you don't stretch it. You can cut it perfect, sew it perfect and ruin it all when you iron it. First set the seams flat (I set on both sides), then open it at the center and press (just lay the iron on it), then just to the right of center, then to the left of center, back to the right - etc - until you've pressed it end to end.
When done ironing, measure it again.