For the majority of my seams, I press all seams to one side as shown below. This makes sections butt up together so seams meet accurately. It is also important if you wish to do "Stitch in the Ditch" quilting.

To do this, always start by pressing the seam flat just as it is sewn. This sets the stitches and fabric before opening the two sections.

Set seam by pressing flat

Position your block so that the section you want the seam pressed towards, is on top (usually darkest fabric), then use the tip and side of the iron to fold this top section over the seam.

Pressing is done from the right side of the block, however always check the seam on the back to ensure it is pressed correctly and lays flat.

Use tip of iron to fold
top fabric over seam

Seam pressed towards
top fabric