Hey Fenster,
The two best methods I've found is:
1-Midsize spray bottle-put 3 to 4 small drops of dishsoap then fill with water-Turn off all lighting(except to see with) Spray completly all infected plant (over,under,stem, and bud as well) -let soak out of the lights and dry for two hours or so. Then return them back to thier light source. This will kill 80% to 90% of all your mites temporaily. They'll be back in about a week and ahalf or two and you will then need to repeat the process. Don't increase the amount of dishsoap, you can damage your plants and they will still be back anyways regardless.
2-No Pest Strip- Place around infected plants -then seal up and leave the room-Let Strip hang out for about 4 hours or so- then remove, seal up strip and put away-Do this for three days in a row. Will kill all mites, if space is not to big, or if too much outside air-This will not kill eggs and may have to repeat process if they show up again.
Many others ways to go about it, but for quick, safe,efficient and cheap all in one effert, these are the best as for as I Know. Wish you great Growing!