Methods and devices are provided for determining a suitable site for sampling physiological fluid. In the subject methods, a potentially suitable physiological sampling site is selected, the fluid flow of the site is characterized and the site is then determined to be suitable based on the whether the site has high or low flow. Suitability may also be determined based on the type of sample obtainable from the site, where the order of the above-described steps may be altered. The subject devices include at least one site flow characterization element for determining the flow characteristics of a potential physiological sampling site and/or at least one sample type characterization element for determining whether the vasculature is arterial, venous or neither, i.e., an interstitial fluid sampling site. The subject methods and devices are particularly suited for use in the detection of physiological sampling sites in the fingers, arms, legs, earlobes, heels, feet, nose and toes. Also provided are kits that include the subject devices for use in practicing the subject methods.