We keep hearing people asking what some abbreviations mean. Instead of answering each question individually, we'll start to answer them and compile a glossary here!
TF literally means 'Time for'. Before the advent of digital portfolios TF would commonly be TFP (time for prints). TF is an exchange of time for photos between the model and photographer. Usually there is no money involved.
TF is a brilliant way to try new techniques out, before using them on paying clients.