Polka dots can be made either by hand, with a purchased stencil, or with craft sponges, depending on how precise you want the pattern to be on the wall. If you want a quick, fun effect and you feel crafty enough to eyeball it, then going to your local craft store and finding little circular sponges would be a fun way to do your project. The distance between polka dots can be completely arbitrary, which means that the final product will be left up to your personal style and eye.
If you want a little more control over how big or small your individual polka dots are, then you can always find a math compass to determine the exact radius of every polka dot. You can also measure out set distances across the wall in a grid and then decide a uniform radius for each polka dot to be, but this will still involve taping after the lines are laid, and it won’t be as easy to get a consistent pattern as using stencils.
The advantage of using a stencil for a polka dot pattern is that it has an edge. This makes it very easy to make geometrically consistent polka dots, and a simple mark to help you remember where the edges of your stencil were placed down is enough to align the next placement. To make your life easier, it’s often useful to use a spray adhesive. This will make your stencil slightly tacky to the touch so that you can put it up on the wall without worrying about taping every time.
The difficulty of painting with glitter depends entirely on what final effect you’re looking for. Most stores will have a glitter finish available as a top coat to add a sparkle or sheen to your base color, but if you’re going for a more textured look, then you’re probably looking for a waterborne acrylic coating with the reflective flakes embedded for that three-dimensional feel.
If all this can’t sate your need for chunky, super-textured glitter, then it’s time to make a trip to the craft store. Find a couple jars of different sized glitter, and mix them together. Then, with a sealing adhesive that dries clear (such as Mod Podge), you can mix the glitter and apply it liberally to your wall until you have your desired texture. These kinds of projects will get messy very quickly so be sure to put down a drop cloth or something similar to catch the falling glitter goop.