I'm in the middle of making a Maya too. I scrounged around and found some great Maya cosplayers out there, and all of them have been more than happy to answer questions for me.
page is translated from Spanish, but Nebulaluben is one of my favourites, and she has a few great posts on how she put hers together. You can also find her on DeviantArt, I PMed her on there and she was great.
also has a small photo tutorial not too far down her page on how she put together her body suit.
As far as fabrics go, I'm using something called scuba knit, which is something like two layers of spandex, so it's got a good thickness without worrying about layers bunching. I'm using yellow and silver spandex, as well as a sort of fishnet mesh for some of the detail.
My pants are made from a one-way stretch suiting material that has a nice gentle gloss to it, with grey suiting for the pockets/side details.
As far as tattoos go, there are heaps of brands out there, but I suggest an ink or liquid body paint, as it makes it worlds easier to get it looking even.
I made her class mod out of a box-that-looks-like-a-book, and kept it functional for storing things in at conventions.
For weapons, NERF are an excellent and cheap place to start, but I have a pet peeve after seeing so many cosplayers with poorly painted, unmodified Nerf. So if you do go there, consider cutting and gluing your gun, sanding off the NERF logo, and using a good paint scheme.
If you need reference images, I have some great, decently high-res ones that I'm happy to share.
If you'd like to be pointed in the direction of a couple of great wigs, I'm happy to share that too.
Hope that helps a bit. Happy to answer more questions or help along the way if you need it.