My baby girl wanted a Tink party for her 4th birthday. Her 3rd birthday was a princess cake so I already had purchased and again used Wilton's doll cake pan. I used store bought cake mix. I would recommend avoiding the "pudding in the mix" cake as it can be to soft to hold the shape well.
I replaced the doll "spike" that is included with the Wilton pan with a purchased Tink doll that I tightly wrapped with press and seal wrap from the waist down to protect it. I did have to cut the hole in the middle of the cake a bit larger than the center "pipe" that is used for baking to make Tink fit. I just used a long thin bread knife and I had no problems with the cake cracking.
I then iced with light green (tinted with gel color) butter cream, piped stars on with darker green butter cream for the top of her dress and then came the fun, roses and lots of foliage. The multi tinted roses were achieved by "stripping" my pastry bag.
Take a spatula full of a darker icing and run a strip of it along the length of the inside of a empty pastry bag and then fill bag with your lighter color. As you squeeze your flowers will be two toned. You can even add a second strip for three tone flowers.
My daughter loved this Tinkerbell Doll Cake! And after her party we unwrapped Tink and she had a new doll. I have also used the same cake pan and basic steps to make a pirate girl cake with hot pink dress and black accents. Also a huge hit.
So buy a doll cake pan and have some fun. Even if it's not perfect I can bet your little girl will love it!