What caused the problems to begin with? What kind of problems did you have with it? Can you pin point the problem?
Is it piecing? Take a ruler and slide it under your presser foot. Line up your needle with the exact 1/4". If it doesn't meet the edge of your presser foot, put a small stack of sticky notes, a small piece of foam or something to act as your guide.
Is your pressing ok? Are you ironing from the top of your work or back?
Always press from the top, that way you will be certain to get the pieces flat. Pressing from the back and cause a "ridge" at your seam line and subsequent pieces won't fit.
Is the pattern correct? Sometimes when you use pattern pieces (if it calls for templates) can warp or be off size during the copy process in printing. I always redraft a pattern to make sure it is accurate.
Even with bought patterns, cutting instructions could be wrong. As a pattern designer, I have a pattern tester test all my patterns for mistakes.....even she can miss something....and has.
Is your cutting accurate? Measure twice, cut once!! Even a fraction of an inch can mean a lot when the block is finished.
What thread are you using to sew with? Do you realize that a thicker thread sewn at an exact 1/4" can take up space in the seam?
If you could post a pic of your work and explain what caused you problems, we may be able to help. Right now I'm just trying to think of different things that I teach my students to ensure accuracy.