There's a definite trend at the moment for gathered skirts & ruffles & if like me you find sewing 2 or 3 lines of gathering tedious & then getting the gathers even arduous, here's a nifty little trick that I use to get a nice even gather. This method is most suitable for those larger expanses of gathering rather than smaller ones in a sleeve head or a cuff for example.
In this example there is a 5/8" (1.5 cm) seam allowance & I've used 3/8" (1cm) elastic.
Step 1. Measure the width or circumference of the area that you are gathering into. In the example above, I'm gathering a skirt into a bodice, so measure the full bodice.
Step 2. Cut a piece of elastic to the width that you've measured, add around 1" (2.5cm) seam allowance for joining them together. (It's actually better to have the elastic slightly too small than too big to get an even gather)
Step 3. Join your elastic so that it forms a circle & then mark the quarter marks around it (fold in 1/2 & then 1/2 again) & do the same for the bodice & skirt (or larger tier if doing ruffles).
Step 4. Align the quarter marks of the elastic with the quarter marks on your skirt. It will look a little like the photograph above. You can add more pins here but there's really no need to & can be quite fiddly unless you have an extra pair of hands to help you.
Step 5. Set your stitch to a long zig zag stitch, you should be ok with a universal needle. (Keeping the stitch long makes it easier to unpick later, changing the colour of the thread makes it easier to see, if you are going to remove the elastic).
Step 6. Take the skirt to your machine & start just behind one of the pins. Make sure that your elastic is within the seam allowance put your needle in the down position so that your needle is acting as an extra hand to secure the elastic to the skirt.
Step 7. Remove the pin, (so that you don't sew over it!) & gently pull the elastic out so that it's the same length of the skirt. (If you find that it's too long a length to sew & control, you can add extra pins at this stage while the elastic is secured with the machine needle)
Step 8. Now start to sew the elastic to the skirt. Take it slowly & make sure that you remain within the seam allowance. Continue all the way around, gently stretching out the elastic to meet the length of the skirt & removing pins as you go. No need to backstitch at either end.
Step 9. The top of the skirt should be the same measurement as the bodice, a little smaller is fine, as you can stretch as you sew. With the right sides together, align the bodice & the skirt, at the quarter marks & pin.
Step 10. Sew with the skirt facing up so that you can see the gathers, making sure that they remain relatively even. It's now up to you whether you remove the elastic or keep it in. I generally remove it but it can stay in on a waistband, probably not a good idea on a ruffled tier.
And you're done, you should have nice even gathers which don't bunch up weirdly in some parts & are flat in others.