Hi there, Im currently working on an asari costume myself. Although i will be cosplaying Samara, and not Liara. However I have come up with a make-up routine that doesnt smudge or wipe off in the heat.
Since its near halloween all these colors come easy:
-note: make sure these are liquids not paint pots. If they are, just add some water and another make up base like a cream-
I first apply a coat of white with a make up sponge and make sure my face is thoroughly covered. Doing a coat of white first will make the colors appear more vibrant and stand out more than if they were jst applied to regular skin.
I think mix a royal blue with a grey in about a 1:2 ratio, being more grey with a hint of blue. However you may have to put in a little more blue because Liara is quite a bright blue as opposed to Samara.
I think go over my face with a blue powder, or a invisible powder. (This will set the liquids and stop them from smudging.)
Finally i take a blue eyeshadow, one to similar colors of the liquids i used and grab an old pair of small holed fish nets. (Fish nets make a great scale like look, and i apply this to the outer portions of my face. and around where i sealed the latex head piece to my head. to blend it a little better.
I then go in and add small details with a liquid or gell eyeliner. Liara has really thin makings that appear as eyebrows, as well she has a ton of freckles under her eyes and around her cheeks, i make these with the eyeliner.
After all that make-up is done, i seal it with a spray (if you dont have a make up spray a light coat of flexible hairspray will do the same.
If you have any more questions feel free to send me a message!
Cosplays planned for AN/13, FE/13
Jeanne - Bayonetta
Samara - Mass Effect 2
Sheik - Legend of Zelda