When stitching 1/4″ seam allowances with a 1/4″ foot such as Patchwork Foot #37 or Patchwork Foot with Guide #57, be sure to use the actual edge of the foot as your guide—if your fabric is peeking out from under the side, it’s extending past the 1/4″ guide. Instead of watching the side of the foot, watch the edge of the fabric as it goes under the toe; this is where you’ll align the raw edges of your fabric pieces with the edge of the foot. Another helpful guide is the 1/4″ mark on your stitch plate, just in front of the foot. By following both of these guides you’ll ensure that your seams are exactly 1/4″, and all of your subsequent joins should match properly.
I always buy two spools of thread, then wind one completely on bobbins. That way I know I’ll have enough thread on bobbins to last until the needle thread runs out. This works for garment sewing and home dec as well as patchwork. For colors I use a lot (browns, grays, denim blues) I purchase full boxes of thread—I can usually get a bulk discount that way—and I always end up using it all. Last summer I purchased several boxes of brown thread for the My Label wardrobe I put together—50 weight for my sewing machine, and 60 weight for my serger. I use three or four spools of 60 weight on my serger when sewing garments rather than using serger thread—it comes in lots of colors and is soft on the inside of garments.