For the beginner quilter or even

for those of us that have been doing it for awhile.
Try to set up your machine so that you see it every day and take a few minutes to just stitch.  Get the feel of your machine, learn the sound of your machine.  AND PLEASE, if you use the hand crank on the side, one direction only.  DO NOT wiggle it back and forth.  You will throw out your tension.

Whyever did I post the photo of a foot with a sock on it?  Kick off your shoes, kick off your slippers and use your foot to operate the peddle on your machine.  You can "feel" it better.  I curl my toes around the front of the foot and I get just the right amount of pressure to sew smoothly.

Don't sit like this at your machine. 

 Here's how you do it

Sit directly in front of your machine.  A great rule of thumb is have your nose directly in front of the needle/presser foot.  Sit up straight.  Make sure your chair is the right height.  If you feel your shoulders tensing up, get up and walk around.

When looking at your machine while you are sewing, keep your eye focused on the foot.  You want to watch the edge where the fabric is.  This is really important for that 1/4" seam allowance or when you sew on bindings.
When you are finished sewing for the day, cover your machine.  Unplug your machine from the wall.  Most machines today are computerized.  Some times we do get power surges.  I don't even trust my power bar.  Change your needle frequently and clean inside the bobbin casing and as far down as your machine allows you to reach.  Make everything you do a habit.
Practice, practice, practice.  It's the key to getting a good 1/4".  It took all of the oldtimes a long time to get there.  Have patience.  It won't happen overnight.