What statistical tool to choose according to your question
XLSTAT has developed a series of guides that will help you in choosing an appropriate statistical analysis method to investigate the question you are asking.
What multivariate data analysis method to use (PCA, DA, CA, MCA...)
What clustering method to use (AHC, k-means, Latent Class Cluster analysis...)
What statistical test to use (t-test, Fisher's exact test, Pearson correlation...)
What statistical modeling method to use (regression, ANCOVA...)