the trick to even 1/4" seams to not to watch the needle, which people tend to do... watch the fabric and your seam guide (whatever kind you use) begin with the fabric right UP to the seam guide (guides are better FOR SOME PEOPLE, than the 1/4" foot, but both are fine, and USING both is fine)... now watch the fabric go into the foot, under the foot and then at the end, it's like golf or baseball... FOLLOW THRU....do NOT let go of the fabric till it is ALL the way thru the foot... feeling like it is done when you get to the front of the foot is the problem....follow thru...all the way past the needle while still controlling the fabric....i know this sounds obvious but it is a really common problem and especially when sewing on an angled piece... we sew straight squares better because it is straight...the seam has to be measured from the needle to the seam, not matter the angle... do not watch the needle...