Here are some slide prepping instructions from Berkeley. 
Place lens tissue paper above and below a microscope slide.
To clean the slide, drop a small amount of isopropyl alcohol on top of the top piece of lens tissue.
Slide the lens tissue across the microscope slide, making sure that the alcohol wipes across the entire slide. You may need something to hold the slide in place to keep it from... well, sliding.
Cut a short piece of double sided sticky tape. Cut this piece in half length-wise so you get two, skinny pieces of tape.
Put some vaseline on one side of both pieces of tape.
Place both of these pieces of tape on the microscope slide about a centimeter away from each other with the vaseline sides facing each other.
After cleaning a microscope cover slip in the same fashion as the slide, place a cover slip on top of the two pieces of tape. Be sure that the cover slip is secure.
Retrieve around 10 micro-liters of microsphere solution. Make sure that this is very dilute. If you can see any opacity, it is too concentrated.
Dry off any excess solution on the edges of the cover slip.
Use top coat nail polish to seal the ends of the channels.