You can sew a perfect circle using an old fashion thumb tack & a cork.

Tape tack to the left of your needle, point up, with good tape (think duct tape vs masking tape)

Put the center of your circle fabric over the tack and gently push down (cut larger than needed)

Smooth fabric under presser foot and lower foot

For your safety hold cork on point of tack

Slowly & evenly start sewing. Let the machine do the work.

Don't let yourself be distracted.
The feed dogs will pull the fabric around the tack.
Sew past where you started to lock the stitches.
Circle should be small & lightweight enough to 'float' on surface. If too heavy drag distorts circle.

I use Karen Kay Buckleys 'perfect circle' templates.... they come in lots of sizes and work very very well.

i use my cricrit to cut out any size perfect circles out of heavy card stock then cut fabric 1/2 in. larger use #5 stitch on my machine an run around the edge of fabric. and draw it to a tight circle and press

cut a circle out of cardboard, same size as the circle you want the fabric to be, fold the edges of the fabric over the cardboard, and use the hand stitching, all around before removing the cardboard. After stitching it all around, press with the iron, then remove the cardboard. There is a tutorial on Missouri Star Quilt Co. It works perfectly... :D

Yes, Yes I just watched a video on the internet yesterday, this is exactly how she was teaching applique .

Baste stitch by hand around template in the 1/4 inch seam allowance and pull tightly to gather. Paint gathered edge with spray starch and press till dry with iron. Ease template out without trying to disturb the turned over seam allowance too much. You can use iron over template plastic like Templar and cut circles yourself if you do not want to invest in Perfect Circles. I have learned this method from Karen Kaye Buckley.

Excellent tip, thanks for sharing.

I like this method...I had my Son in law who works in a machine shop shave down a set of metal washers that work great. Mostly for smaller circles. If I need a big circle I use this technique.
http://www.youtube.com/watch?v=8ChE9UBWA8A

That's what I do, and they come out perfectly each time.

Great bunch of ways of doing the circles must try them