Having a fairy godmother is what every chimney sweep needs. Many don't know this, but the name "Cinderella" was given because the young girl's job was to sweep the fireplace. The cinders would end up on her face and clothes, hence the nickname "Cinderella." The one being that helped Cinderella rise to the top was, of course, her Fairy Godmother. If you have a little girl dressing as Cinderella this Halloween, you could complement her outfit perfectly--and get in on the fun yourself--by creating a simple Fairy Godmother costume.
Put on a grey or silver wig. A fairy godmother has earned her place and position. She is not a young girl. Cinderella is someone she has taken on to help and protect. She worked her way to get to a position of helping others. Make sure you show her due respect and dress properly for the age of a true fairy godmother.
Keep the make-up minimal. A bit of blush, glitter on the face and neck and pink lip gloss will do just fine for this costume. Too much make-up ruins the fun and innocence of this silly but beautiful character.
Put on a simple blue dress or slip. This will simply be support underneath your costume. (One must always take extra precautions when dressing up as a character that little girls adore!)
Beg, buy or borrow a blue robe. This could even be a converted (or dyed) graduation gown. An evening gown that is light blue in colour can be adapted to work, as well. An oversized nightgown may even do the trick. You could also dye an old cloak and an old hoodie in unison. Place the hoodie on first, then wear the cloak above it. Since the fairy godmother had a hood as a part of her costume, this will flow perfectly--especially if the pieces are dyed to match one another.
Tie a red or pink scarf into a bow around your neck. This should appear to pull the entire "robe" look together. The scarf should be tied in a perfect bow, as you would tie a ribbon.
Put on matching blue slippers. These shoes can be simple; the glass slippers are for Cinderella. The fairy godmother has lived and learnt. She prefers simplicity in footwear.
Grab a wand with a star at its end. This is essential. You must have a wand in order to make wishes come true. You can also add another whimsical prop to your costume, such as a small pumpkin that will later be transformed into a carriage.
Say "bibbity bobbity boo" as a response to almost any question asked. While this will get annoyed after two tries to get a straight answer from you, it will delight young children as you first start to do it.
Sing fairy-tale songs while in costume as a special way of delighting young children. They will be enchanted by you.
Don't lose your cool while in costume. Children will be watching you at Halloween, and very small children will not understand that you are not the character your costume portrays you as being. Keep in mind that the imaginations of some little ones may be affected by how you behave while in costume.