I would use Elmer's Washable School glue (white), but with a pinpoint tip screwed on:
http://www.purpledaisiesllc.com/Fine..._Glue_p/69.htm
The above are the glue tips that I have, and they are wonderful for squeeing out just a tiny drop of glue at a time. To keep the top flowing between uses, I placed a sponge in the bottom of a jar, added water to keep the sponge damp, and store the glue upside down in the jar. The glue does need to be set with an iron as you go (but it's quick).
The advantages of the above are that it's not at all messy, if you don't like the placement you can still lift the piece up and re-glue in a different spot, and it won't distort your pieces.