Fluid Medium-available in matte (matte has a substance in it to dull the gloss. If you apply it in layers it has the tendency to look 'cloudy'), gloss (if you get a high quality product like Golden or Nova Color, you have to add several layers for it to look high intense gloss), polymer medium, fluid matte medium, fluid medium-you can use these for collage but I have found them to be too 'wet' of a glue. What I like to do is to add any of these (my fave is either gloss medium or polymer medium) to my acrylics to 'extend the amount of paint' that I have (but do not buy what they label as extender as that extends the drying time-eek!).
Glazing liquid-available in satin, matte or gloss. I have a hard time telling the difference between the satin and gloss (by finished work alone). Use these with any kind of acrylic to create transparent, colored glazes.
Acrylic Gesso: An acrylic ground that is flexible and is used for prepping or priming surfaces. Available in several colors including white, black, beige, brown, etc...
Acrylic Gel medium: Used to thicken or thin paints. Used as a texture gel. Also used as a collage adhesive. Available in a variety of 'thicknesses' most students seem to prefer soft gel gloss or regular. Remember you can buy just one kind and if you want to thicken it, leave it on your palette for an hour or so. If you want to thin it, add polymer/gloss or matte medium to it. The best way to apply it is THIN and to the back of your image. I place the image then on the surface I am gluing onto & rub w/ a paper towel or rag. If working in a book, i do not place glue over the top of the image. This will help to prevent pages from sticking. Also, you only need ONE kind of gel medium.
Acrylic varnish: available in 3 finishes: gloss, matte and satin. Seals the surface to protect it. I never seal or coat the inside of my book pages. If I'm working on canvas or a surface that does need to be protected, I'll seal it using the Gloss medium and Varnish combination.
There are other mediums out there used for various reasons and purposes. Some of my favorite additional texture mediums are-
Clear Tar Gel-to drizzle, fling, flick, write, draw, etc... with. I love using this stuff. Paint with it. Put it in a bottle. Write in it. Embed things in it. Draw or write with it. Make marks and doodles with it. Let it dry raised. Comb into it. Splatter with it. Pretend your Jackson Pollock with it. etc... I've used it alone. I've mixed it with paint. I've painted over it. I've painted under it. Texture love in a bottle.
Micaceous Iron Oxide- Yum that you can't eat. Shiny, mica filled surfaces. Paint with it. Mix it with your paint. Paint over it. Paint under it. Use your caran d'ache neo art watersoluble wax pastels with it. Write into it. Draw into it. Make marks into it. Stencil with it. Gritty, but FUN!
Don't leave out stamping, stenciling, painting, prepping, writing with/into, drawing with/into any of the above mediums like gel medium, gesso, or the fluid mediums. With a handful of favorite products, you have a whole rainbow of colors, textures and applications at your fingertips!