Hand piecing
Although I do occasionally machine sew my quilts, most of what I do is still hand-pieced.
I use a small running stitch, and take one back stitch at the beginning and end of my block. Also take a back stitch each time I pull my thread up. Originally, that was to help strengthen my seam because I had not marked my seam lines. As another poster said, drawing a light guide helped me to keep my seams straight, and now I just "eyeball" the seams.
Whatever template you use, make sure you start and stop 1/4 inch away from the edges so your seams will nest together. And the best advice (for me) was to make sure your rotary cutter or scissors are sharp. You'd be surprised at how easy it is to distort some or all of your pieces by "chopping" instead of cutting.
One of the things I like best about hand-piecing is that it is much more portable than a machine. Yes, it does take longer, but I'm OK with that.