So I've been doing a lot of research for this, and I'm really lucky in that I have Belizma (Teacup_Erinyes) and Hazel (Squiddley) helping me. I'm also using Angelphie's marvellous detailed information on how she made her Tinker Bell costumes, and she's given me advice too! So I've had lots of help.
I bought New Look's pattern in 6468 for this dress as it has lots of panels that are a good guide for editing the hem of the dress. It's going to be quite tight-fitting but that's the look that I want. I'm requesting fabric samples tomorrow from fabricland.co.uk of their suedette in emerald green and bottle green, I think the emerald will work quite nicely.
Angelphie's wing walk-through is very helpful, but I'll also be using JiaJem's wing tutorial for the harness; http://jiajem.com/tutorials/wings/ I may use clear vinyl for the wings, but I'm also thinking about using tights stretched over the frame,or using other fabrics. We'll see what I can get!
I've found this tutorial as well for editing the hem, which should hopefully go well, and hopefully I can use a similar technique for the neckline!