Vacuum users today are offered a wide variety of commercially-available vacuum instrumentation. But selecting adequate or best instruments for a particular application can sometimes be a daunting task since the only well defined parameter may be the cost. This talk will provide information to help users select instruments that will best meet their needs. This will include a brief description of thermal conductivity gauges, capacitance diaphragm gauges, micromachined electromechanical pressure gauges, ionization gauges and residual gas analyzers, and a discussion of the relative advantages and disadvantages of each type. Beyond this, experimental procedures will be described that can be carried out in the user's laboratory to determine important characteristics of specific instruments and, in some cases, make adjustments to optimize performance.