DublB's X method works ... you have bias on the outside edges of yoru square in a square.
I used it for this quilt, as I needed to get the pattern facing the right way in the setting triangles. Butterflies for Comfort
The \ method ... you have bias on the side you are stitching right away, leaving straight of grain on the outside edges.
Either ways, you have bias to deal with ... spray starch the fabric and it'll help keep it stable while you are cutting/trimming.
If not doing overly large sq-in-sq .... I like to PP them .... gets it all really nice and precise.
W4Me .... how large is your cross stitched maple leaf centre?