I've been running into a bit of trouble getting acrylic highlights to pop. I'm not sure if this is chemically sound, as in it might do goofy discoloration over time, but it's something I tried that worked pretty well. To get really bright highlights in my acrylics I added neon colored gauche into the colors I mix for highlights. For instance, neon pink gauche into a bright red acrylic.
It could be the kind of acrylics I'm painting with are making me fight for colors. It might also be how dark I tend to go makes me fight harder as well. At any rate, I've found a work around for it for now. Might be useful to someone.
Real paint does not work like Photoshop. Both are lots of fun though.
Also, it is slowly sinking in that you can mix mediums. Seems obvious, but I forget the obvious things when I'm doing. Looking back later it's suddenly all so clear.