  We summarize our latest developments in perturbative treating the effective
theories of strong interactions. We discuss the principles of constructing the
mathematically correct expressions for the S-matrix elements at a given loop
order and briefly review the renormalization procedure. This talk shall provide
the philosophical basement as well as serve as an introduction for the material
presented at this conference by A. Vereshagin and K. Semenov-Tian-Shansky.
