A very easy way to make ruffles.....
 

I saw this method demonstrated on YouTube, sorry to say I lost the link. However it is so simple and effective I thought to pass it on. Here it is, set your tension to #8 and stitch length to #5. If you cannot do either of these things then this won't work for you. However once things are set just sew along the edge. Do not back stitch and be sure to leave at least 4inch thread tales on either end. The gathers are easily then adjusted as needed. I recently needed to add ruffles to a curved hem on aprons, this worked great. I just pinned at the center and ends of the seam and adjusted the ruffles as I pinned along the perimeter. Of course this is basically a basting stitch so you do need to over sew the gathers with a regular stitch length and tension. I have a ruffling-foot and a gathering foot but I found this a very easy solution to how to get the gathers to fit in the seam you are trying to match it with. If anyone has a link to the You Tube video on the gathering technique please post it so they can get credit for this idea.
Another tip I found helpful is if you have a serger and can do a rolled hem stitch, then I just finish the bottom edge rather than hem it. I use all four threads, widest seam width setting and a short stitch setting. Then I get out some bright variegated serger threads and finish off the bottom edge this way. It adds a pop of color, and gives the edge a clean hemmed finish. It adds a decorative edge to the ruffle. It is also a great and easy way to do a quick finish to kitchen towels and wash cloths.

Check your instructions on your serger. My serger will make ruffles. That would have been the easiest of all.

I don't change my tension but that is the way I've made ruffles the 60 +/- years I've been sewing.

I was taught to do two rows of basting (similar to this method), for gathering. Pin each end, to seam line. Then fold to center of ruffle, matching center of seam line. Pin. Then fold to center of each piece, between pins. Match and pin. Depending upon the expanse to be sewn, this may be done several more times, before adjusting ruffles and sewing together. Been sewing over 50 years.

When my kids were little and I sewed a lot of clothes that was the way I made ruffles!

I second the two rows of stitching. I have done this nearly 60 years. I've even used three rows on very full garments. I would never use a single row on anything.

Ditto everything Neesie said. I also still use many of those techniques we had to master in junior high home-ec class to get a decent grade.

I'm with Neesie. I was taught this way of making ruffles and that is the only way I would do it. One thread only
is likely to break then you have to start over. I never adjusted the tension, just used the longest stitch the machine had. I have been sewing 52 years. Some tips are good and sometimes the old ways work better.

That's how I make my ruffles, too.

The way I have used recently is to zig zag over a thick piece of thread (some recommend dental floss) without catching it and then gather to desired length and when done sewing, pull out the thick thread/floss.