Precision, Precision, Precision.
Cutting, seaming, pressing, squaring up a block as it is being pieced. Squaring up the finished block.
Pre washing fabric and buying good quality fabric are
extremely important factors in making a great quilt.
Making a quilt is a combination of a lot of factors, any one thing not done correctly can disrupt the entire process.
A quilter needs to be a perfectionist to produce a great finished product. Practice makes perfect.
Start with simple patterns, few seams to match, and work up to harder patterns. Starting with too hard of a pattern can be discouraging. :-D