I decided to base my tulpa off of Fluttershy. I've told her she can deviate however she wants, and I've made sure she knows that she is based off of Flutters from MLP but she doesn't have to be just like her. In fact, if she was, I'd probably be disappointed. Anyways, I'm using JD's Tulpa Method, where you do all the visualization first, and then instead of forcing personality traits, you parrot your tulpa in the wonderland as to you think they would react to certain situations. Then once you get used to doing this, you stop- no more parroting, ever, and they should begin to do things on their own. Finally is imposition / vocalization / possession, all that fun stuff!
Anyways, I had my first visualization session last night. I got my wonderland done. It's a sunny, breezy meadow with a forest in the back, one tree in the wonderland itself (mainly so it's easier to visualize) and some daffodils and butterflies on the ground. There's a tire swing hanging from the tree, and the sky gets darker the closer it is to the forest. I plan to expand this more, but probably only after Flutters starts showing signs of setience.
The point is that after I got all that done, I started with a foggy outline of her. Completely white, like one of Rarity's mannequins, to make it easier to build up as I'd already have a solid form down. I fell asleep right after I started to visualize that, and woke up about six hours later. I feel really, really bad about falling asleep on her, but I did write 'T' for Tulpa on my hand so I remember to narrate to her throughout the day and I plan to do a forcing session when I get home.
I'm doing a mixture of open and closed eye visualization, as according to JD open eye visualization makes imposition a lot easier once you get to that stage.