Learn Survival Flemish
Although there is currently not a specific Flemish phrasebook, Wikivoyage users have collectively created annotations to the free Dutch phrasebook to distinguish differences between Flemish and Dutch. The goal is to make it possible for travelers to "get by" while traveling in areas where Flemish is spoken using the Dutch phrases along with Flemish vocabulary and pronunciation.
Wikivoyage phrasebooks are available in many languages and each one varies in depth and detail. Most of the phrasebooks include a pronunciation guide, a general phrase list, information about dates and numbers, a color list, transportation-related phrases, vocabulary for shopping and phrases for eating and drinking. Some are even more in depth, and all are free!