This is a tutorial on how to make your own mane pattern, I used
's pattern as an example but you can use other variations.
Here is a great MLP Eye tutorial! [link]
Often times, especially with heavier/fluffier fabrics, it helps to enlarge the mane shape a little further (it's hard to say how much exactly, since ponies will be all different sizes, but it shouldn't be a huge difference) after the scaling step to compensate for when it's turned right-side out and stuffed after sewing.
Also be sure that you make a test pony before you are dead set on your pattern, this way you work out all of the kinks before it is all finalized!
If you are struggling with the tail use the same method! c: