I made the mistake of cutting down my blocks for a particular size and lost my points.
So it is better to use a larger block than called for than to cut them down.
If the block is out of square,now thats a problem.
I have found that when new at quilting, use an Eleanor Burns pattern.
Her patterns just seem to fall togather correctly.
Be sure to watch lots of videos on Quilters TV for instructions.
Good luck and have fun even if it dosnt turn out perfect, think of it as a learning experience.