When I start anything new that I don't know much about, I am a bit of an obsessive researcher.
Before I started my chiffon blouse, I scoured the internet for as much help as I could find in sewing with the difficult fabric.
Here are a few of the links I found that proved really useful and made a massive difference to the outcome of my first chiffon project. The tips here all really work and I'm posting them so I don't lose them the next time I want to tackle a chiffon project.
First up, a Sanda Betzina tutorial. Excellent.
Next, this Professor Pincushion tutorial (youtube video), also really helpful, especially about managing the puckering/tension problem that can happen.
These tips were also useful (sewing.about.com).
Also this, including a good rolled hem tutorial (thesewbox) (using a rolled hem foot - FYI I actually ended up doing it using a normal foot by turning under and sewing a narrow hem, trimming close to the stitching - carefully - pressing, and then turning under and sewing a second narrow hem and then pressing again. It took longer but I felt it gave a better finish as the hem was a full circle and was very curved, I couldn't get a nice even feed using the rolled hem foot).
and of course, Threads Magazine has some great tips.
Most of the tips in the three links above are the same, and I can certainly say, you have to pay attention, they all make a huge difference to the finished result.
And of course, press, press, press. Pressing the seams at each step helped to remove any remaining puckering (and there was quite a bit of puckering, although much less when I applied all the information above) and gave a nice flat finish to each seam. I first came across the term Pressinatrix on the wonderful poppykettle blog and I am also now a definite convert.