Re: How to glue fiber tissue paper against real paper?
Acrylic mediums are acrylic paint without the pigments. They come in all different viscosities, and can be used as adhesives and as paint mediums. You would buy them in an art supply shop or online. Liquitex and Goldens make really good ones. There's also a much less expensive medium that's made for acrylic wall paints called Floetral. Most acrylic paint artists use it as an acrylic pouring medium. That you can get in any hardware store that sells interior paints! But I don't know about the water content.
Personally, I mostly use Goldens products, and I particularly like their Gloss Medium and the Matte Medium. They are good "glues" for collage, and I also use them to mix my heavy-bodied (tube) acrylics to the consistency I want.