Make yourself a cheap pleat board, out of inexpensive poster board... Make sure to mark the dimensions ((front size and inside size that)) of the pleats ((ruffles)) that you want. on the board and keep it the same for each one, it should look like a folding accordian when your done, but it should not look like a fan, if it looks like a Fan... it wasn't done correctly.
For instance, lets say you want to do one inch pleats, the front flap should all be one inch, but when you go in to tuck the fabric it should be about a half an inch inwards, this way it stays, then pin the tops and bottoms of the fabric down. Before you move the pleats off the board, make sure to take an iron, and iron down the fabric, then pin the top so that it holds properly. when you finished the part that you've finished and need to make more pleats, remove the pleats carefully, and place your last finished pleat onto the board where the first one was, and continue the process to make pleats.
If this totally confuses you, which I might have done you can im me on aim at SugaredPixieStix, I'm more than happy to help out ^_^
-Jae