There are lots of ways to starch doilies. I normally use Revive Instant Starch Powder to starch my doilies. This is the way its done.
1. Take about 2 cups of water in a vessel. Add 1 tsp of starch powder and about 1/4 tsp of salt to it. Salt is added so that the colour of the threads doesn't spread. This is useful for doilies made with more than one-coloured thread.
2. Bring this to a boil. Allow it to cool completely.
3. Dip the completed doily in this starch water.
4. Squeeze out excess water from the doily WITHOUT twisting it.
5. Stretch the doily on a pillow and pin it according to desired shape, using pins having beaded heads.
6. Finally, after the doily dries, remove the pins and iron it.