Take it from me and save yourselves and your children a lot of discomfort.
Don't dress your child up as an ice cream cone (ask my younger sister, Chani).
Don't dress your child up as a computer (ask my sister, Sorele).
Don't dress them up as a scarecrow or watercarrier (personal experience - advice free).
Some more no-no-s: A bottle, a crayon / magic marker, doll in cellophane wrapping. In short, no costume that will prevent a child from: eating, holding a shalach monos basket, talking, getting past the doorway frontways, breathing and other necessary functions [delete whatever does not apply].
If your costume requires painting a face, avoid: cocoa paste (phooey!) or even a burnt cork. It hurts! [Again, firsthand experience.] Shoepolish?
And now some DOs.
If your daughter is aged 3-8, we have something super- original, comfortable, and very versatile suggestion, sure to find favor: a kalla.
That's for your three-year-old. Don't worry, the repeat performance will have a different name: at four she can be Malkat Esther [and why they call it that - `the Queen of Esther' - I have yet to learn. No one calls Vashti Malkat Vashti].
The following year she will have turned five and the costume still fits. This time she can be called Queen Shabbos and all you have to do is add a crown with a picture of a challa and a silver foil Kiddush cup.
The little queen turns six and the gown still fits. This year you can pretend she is a snowwoman. Of course, the gown has seen much wear and tear, but not to worry. At this point, the holes are to your advantage. Stuff them up with cotton balls for a realistic effect. You may have trouble pasting a real or imaginary carrot on her nose, but a thick woolen scarf around her neck will get the message across even if the carrot does fall off. Mittens optional.
Our young lady has turned seven and disdains her former costume. By now, the white dress is knee length - perfect for a nurse. Her accessories, simple enough for any mother who by now has half a dozen more children, give or take a few: a stethoscope which you were wise enough to acquire last birthday when you bought her a doctor's kit, and a headband of white bristol with a red Mogen Dovid. Perhaps an armband, if the dress is not convincing enough.
The seventh year is shmitta. You give the girl a rest and let the costume go to the next kalla down the line who can begin the same process all over.
We are still left with our kalla-moid to masquerade. We suggest: age 8: a pretty little Dutch girl. Black skirt with colored bands (crepe paper) all around, a white blouse, vest, hat, clogs.
Age nine: gypsy. Repeat of previous year but replace hat and clogs with all the jewelry you can find or borrow, the more the better. Some colored scarves.
Age ten: flower vendor (vendress?) vat mit de dress? Ditto plus basket of artificial flowers.
Age eleven: balloon vendress. De same von dress with balloons which come cheaper by the dozen.
When our little queen turns bas mitzva, she will surely not want to dress up any more and your problems are over, rather, they are just beginning - though not localized to Purim ("Ima, I have NOTHING to WEAR!").
So who says Purim costumes are an expensive matter?
If you're not quite happy with our suggestions and want something more original, call my sister Sorele.
If you have the idea but don't have the time to make the costume, call my sister Rina.
If you have an original idea, you have the time to devote to making the costume, but don't have anyone in particular to dress up - call ME!