Karen, Terri and Chris are right - patience is the key (as much as we want it done yesterday, we know it's hard to be patient!)
One thing that helped me a lot is that I go beyond the 'duh' of the mistake and really try to look at what happened and why - that's how we learn (and I'll be learning this my whole life, I promise :wink: ) Consistent seams were an early problem for me; I tried every trick I came across, which tended to be part of my problem. I finally chose one foot, one mark as my guide and my seams have been much better since.
I highly recommend getting an Eleanor Burns book, either from your LQS, the local library or online. Her instructions are great for beginners; her pieces tend to be oversized so you can 'square them up' to be perfect and her patterns tend to make it easy to be successful. Her website is
http://www.quiltinaday.com You can also see a lot of her videos on her website and on
http://www.quilterstv.com - the videos along with a book will help make the techniques clear.