Take the time to develop good habits and techniques right from the beginning instead of rushing to finish a project. For example, fold carefully before you cut and then cut as accurately as you can. Practice so that your scant 1/4 inch seam just comes naturally to you. Press (not iron) seams being careful to not distort the block, then square up carefully. Those little tiny, seemingly insignificant steps, make so much difference in your finished project.
One final thought once you get a little experience, take time to carefully read your pattern BEFORE you start cutting, sewing and so on. I take a yellow marker and highlight important points so I understand exactly what the designer had in mind. Why? Because I have made some really dumb mistakes going off half cocked instead of taking time to read and plan ahead. LOL