The band (the section of the pick that wraps around the fingers like a ring) should be fitted to the front of the finger using a pair of smooth pliers so it holds on comfortably, neither so tight that it constrains the finger nor so loose that it begins to fall off while playing. Make sure it is clear of the finger joints so that it does not impede the ability to bend your fingers.
The second area needing adjustment is the blade (the section of the finger pick that comes in contact with the strings). While there is variation in preference as to the length to which the blade of the pick should extend from the finger, it is generally recommended that you keep the length only a slight extension from the natural length of the fingers, emulating finger picking with bare hands. To achieve this, bend the blade to the contours of your finger tip, imitating the shape and leaving only a small extension from the actual end of your finger.
When placing your hand in playing position on the strings, you will probably find that the finger picks will need another adjustment in order to make a square contact with the strings. It is recommended that you bend the middle section of the blade so it protrudes at an angle from your fingertips. This will give you the ideal square contact when picking. Experiment with gradual adjustments to get an angle consistent with your fingers' natural picking technique.
Finger picks come in several materials and thickness, with prices ranging from $6 to $60, at the time of publication. Nickel and silver are recommended. Avoid plastic finger picks, which give poor tone and are not adjustable. Thicker finger picks will have a longer life and produce strong tones.