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 softer on the inside of garments.