As a seamstress, I know a lot of tricks for working with fabric, and a great trick is this simple ways to make ruffles. Here's a video of the whole process, if you'd like to see it done. Ruffle Video
Cut a piece of fabric about an inch wide by as long as you want. The finished ruffle will be less than half the length of the original piece, so plan accordingly.
Step 2 (Using Machine)
If you are using a sewing machine, set the machine so it makes the longest possible stitches. Without locking the stitches by sewing back and forth, sew a line down the middle of the strip lengthwise.
Step 3 (Using Machine)
Find the bobbin thread (it's on the back of the fabric) and gently pull it to start the ruffle. If it doesn't pull easily, try the other thread. Keep pulling, adjusting ruffle downwards, until you have ruffled about half of the strip. Tie the two threads into a knot to secure. Go to the other end, find the bobbin, and repeat. Once the whole strip is ruffled, adjust it to the length you want it and tie the other end off to secure.
Step 2 (No Machine)
It's just as easy to make a ruffle with just a needle and thread. Knot the thread on the end and sew down the center of the strip lengthwise. The stiches can be 1/4 - 1/2 inch long, and uneven is fine. Once you get to the other end, pull the fabric down the thread to create a ruffle. Adjust the ruffle of the fabric so it is the length you want and then tie off the thread to secure.
You can also use this same technique to make a ruffled medallion or flower.
Instead of sewing down the center, sew down one edge of the strip of fabric. When you ruffle it, it will form a circle.
Have fun and let me know if you have any questions.