Any microscope will do, but a compound microscope is the best kind for observing microscopic, transparent specimens, such as dust mites. You can buy a compound microscope online or from a retailer that sells them to schools, hospitals, and research organizations.  You can also acquire a cheap microscope with a 10x magnification lens from a toy store, hobby store, or thrift store. You need to use at least 10x magnification when viewing dust mites under a microscope. Using a clear piece of tape, pick up clumps of dust from surfaces such as shelves or the floor. Put the tape on the slide under the lens of the microscope with the power set to at least 10x magnification.  Dust mites are 0.3 millimetres (0.012 in) in size, so they can’t be seen with the naked eye. Use a lint-free, microfiber cloth to handle the slide to avoid getting fingerprints on the glass. Carry the slide between your thumb and forefinger by its sides rather than by the top and bottom. The stage is located at the front of the microscope under the objective lenses. It’s a flat, square platform with metal clips on it for holding slides. Gently lift the clips and close them over each end of the slide to hold it in place. Don’t force the slides under the clips, as they are fragile and can be easily broken. A power switch on the bottom controls the light. Use the dimmer switch by pushing it forward and backward to adjust the lighting. Adjust the light intensity to low with the dimmer switch at the bottom right of the microscope. When you turn the microscope on, increase the light intensity to a level that isn’t too bright or too low. A ring-like object called the diaphragm lets you control the amount of light that reaches the specimen. You can rotate this with your hand to adjust the amount of light under the specimen. It’s located under the stage. You can rotate it by simply turning it with your fingers. This is the level at which dust mites can be seen. If the dust mites are still out of focus, increase the power objective until you see them clearly. They have long hairs along the edges of their bodies and short hairs all over their bodies. They don’t have eyes or antennae.  Under a microscope, you’ll see dust mites crawling all over one another. Dust mites’ mouths resemble heads.

Summary:
Obtain a compound microscope with 10x magnification. Collect samples of dust and put them on a slide. Put the slide under the stage clips. Plug in the microscope to turn on its light. Rotate the nosepiece to the 10x power objective. Look for clear, oval-shaped arachnids with rigid bodies.