My advice from one newbie to another:
1. Figure out exactly where you need to sew to make a 1/4 inch seam and either adjust your machine's settings or mark it in some way (there is a difference between a scant 1/4 inch as well)
2. You might as well name your seam ripper now (I named mine Jack)
3. Always stick to the same ruler brand when cutting because accuracy is important (they are not calibrated I promise)
4. NEVER CUT WHEN TIRED (Can you tell I've screwed up a few things because of this?)
5. Take a class from a teacher who makes sense to you because we don't all learn the same way (or have a quilting buddy who can guide you)
6. Get extra fabric just in case (I am still buying a little extra fabric for those "oops" moments in cutting)
Everyone's learning curve is different. If you've been sewing a long time adding quilting to your arsenol may be very quick. If you are just learning how to drive your sewing machine it will take longer. Just realize that and give yourself a break when you are ripping something for the nth time.