I use an Angler 2 from Pam Bono so I don't have to draw lines. Connecting Threads has a Seam Guide that is similar but costs much less. No affiliation, just use the first one and have ordered the second one. This makes the process go a LOT faster. The first one is good for squares up to about 7" I think, the second one only 4". These may or may not help you depending on what size you're working with.
Happy stitchin'.