Don't attempt the complicated parts of patterns if you are too tired or distracted. Stick to the easy stuff at those times.
Same goes for cutting. Be sure to read the pattern thoroughly before you start cutting.
Don't freak out if your pieces are a smidgen off. Once it's quilted and washed, the puckering will hide a multitude of mistakes.
Until you gain confidence, match the bobbin thread to the backing fabric. Also hides a multitude of mistakes.
Don't be afraid to experiment with other people's suggestions. Everyone has their own comfort level and what works for them may not work for you. Do what works for you!
When washing a long length of fabric, fold as on the bolt, fanfold into a smaller length, say 1 yard or so, pin w/safety pins every foot or so. Wash & dry this way and avoid a tangled mess.
Relax and enjoy your hobby!