statistics: Statistically, for every four-leaf clover in a clover patch there are approximately 10,000 three-leaf clovers. This large number can appear daunting to some, but once it is understood it should actually provide encouragement.
Clovers are fairly small, usually measuring, at most, an inch from leaf to leaf. Assuming each clover occupies 1 square inch it only take an patch covering 100 square inches, 8'4" X 8'4" to give you 10,000 clovers. When you consider that many clovers will be smaller than 1 square inch, and that they are not uniformly distributed, but often crowd together and overlap, the space required to accommodate 10,000 clovers becomes trivial. Indeed, any clover patch that is large enough for you to lay in with your arms and legs outstretched should be large enough, statistically speaking, to have at least one four-leaf clover in it. It is important, however, to not put too much weight on these statistics, for while they give good general idea of the clover density required to find a four-leaf clover, it gives the false impression of uniform distribution.
Four-leaf clovers are rarely alone. Clovers reproduce both through flowering and by sending out stolons. Stolons, often called runners, are roots that grow outward horizontally from the clover and then sprout into a new clover a short distance from the parent clover. These new clovers are genetically identical to their parent and thus are more likely to have four leaves. Additionally, the other clover surrounding a four-leaf clover will also have been exposed to the same environmental conditions, which may cause a somatic mutation leading to the formation of a fourth leaf.
looking: Because four-leaf clovers are often found in close vicinity to one another, the most efficient searching technique that I have found consists of two parts. First, do a walking survey of the area. Move slowly, and deliberately, but don't get locked into a small area. Move around, look at the different patches from different angles. During this step it is counter-productive to try to individually assess each clover. Instead look at the patch as a whole and train yourself to notice breaks in the pattern of three leaf clovers. Once you have found a clover this way, or you get tired of walking around, sit (lay, squat, kneel) down and examine the area more closely. Now you can address each clover individually, gently move them to the side to see if anything is hiding under them, separate the leaves of clovers which are intertwined.
For me, this method of searching is desirable not only because it is effective in finding many clovers, but also because of the complimentary types of reflection it provides. The way the Zen process of looking without looking, searching for the individual while surveying the whole, compliments the intimate meditation on each individual clover.
impostors: It can be frustrating when a clover conspires with his friend to play a cruel joke on you by arranging their leaves together to give the impression of a four leaf clover, until you push them apart, your hopes dashed, cursing yourself for having been fooled by plants. But take heart in knowing that although you did not find a four leaf clover, your attraction to this impostor still represents a honing of your ability to pick out group of four amongst a sea of threes.