I use a glue stick. You don't have to iron it to "set" it, and if you goof on the placement, just lift it and replace it. Doesn't muck up my needle or machine.
However, sometimes the glue application will go beyond the 1/4" seam allowance. When I open the fabric to iron it sometimes I have to use my fingernail to make sure I've opened it to the seam instead of fabric glued together. The other word of caution is that I use an old iron with a cover on it because I don't want glue mucking up my new iron.
I buy Office Max brand glue sticks which box indicates both "permanent" and "washes from fabric". I also did a check to make sure it washes out before I continued.