I remember feeling like it was impossible to get my blocks in my quilt top to match up and be crisp, until I learned how to nest my seams between blocks and rows!
"Nesting Seams" refers to two rows having seams sewn right side together after having been pressed in opposite directions. This helps the seams to line up and "lock" into place while being sewn on a machine to help maintain points in your quilt top.
Many patterns help you to nest your seams by indicating which direction to press the seams for each block or row. My Shimmering Sun Quilt pattern does this, so I will use it as an example!
In this pattern, the seams for each row are pressed in opposite directions:
As you place the rows right sides together, each seam will match up with the seam in the opposite row and fit together, almost like a puzzle piece.
Before taking the rows to sew the seam, I find it helpful to clip the nested seams together. You could also pin or glue them.
As you sew, make sure the nested seams go under the presser foot together. When you're done with the row, press, and admire your perfect points!