penticostlisland.net has a guide to speaking Bislama.
A reference written by Terry Crowly
A Dictionary compiled by Terry Crowly
86-page PDF English-to-Bislama Dictionary from bislama.org
Because most of the vocabulary is based on English, English speakers will be able to understand a lot of Bislama from contextual clues. Wikipedia articles are a great place to find written Bislama on hundreds of topics.
Language Beat has a series of Bislama lessons.
A short introduction to Bislama
A few missionaries talk about their experiences learning Vanuatu.