when cutting fabric i only fold the fabric once otherwise i never have accurate cuts - that second fold line just put in too much inaccuracy.
if i must cut thru 2 folds of fabric i press the fold lines to make sure they are perfect so i can keep a 90 angle.
i also use 1/4 foot and both of them have guides on them.
the first one i use for 1/4 seams
http://cgi.ebay.com/Brother-Baby-Loc...rkparms=65%3A1|66%3A4|39%3A1|240%3A1318|301%3A1|293%3A1|294%3A20 0
the second one i use for 1/8 seams (i use the hole on the left and use that edge for the guide) or 1/2 seams (i use the hole on the left and use the guide plate to maintain the seam)
http://cgi.ebay.com/Singer-Featherwe...rkparms=65%3A1|66%3A4|39%3A1|240%3A1318|301%3A1|293%3A1|294%3A20 0