Sampling is the process of selecting a subset of individuals from within a population to estimate characteristics of the whole population. The sample size should be large enough to minimize sampling error and be representative of the overall population. An appropriate sample size is typically between 30 to 500 individuals according to guidelines. The sample size can be calculated using formulas that consider the population size, desired margin of error, and confidence level. It is important for the sample to accurately reflect the diversity of the target population.