It can be done in light polluted or dark skies. The easiest way to observe is with the unaided eye. Other methods of observing include the use of binoculars, telescopes of all types, CCD cameras and even special sensors if desired. The skill of locating the same star and estimating its brightness as compared to others are well documented in the references listed below. The time frame for taking data can take hours or up to years depending on the star or observing program in question.
Various organizations have forms to fill out on how to take and submit data.
These organizations are also listed below. Some of these organizations have special interest groups such as CCD, photoelectric photometry, eclipsing binary stars, visual, sunspot, sudden ionosphere disturbance, nova search, super nova search and RR Lyra observing programs. This allows students to learn the scientific process and develops skills in science, math, computing and other areas. Variable Star page - A good place to start. Takes about 15 minutes to go through it.