It's really hard to find resources for Teochew! There are two good apps in the Apple App Store, one called 潮人潮Apps by a HK organization that has some good, lengthy dialogues to study (translations are in Cantonese), and another called WhatTCSay by two overseas Teochew that is a very extensive dictionary (arranged by topic) with recordings of their pronunciation. Other than that, here are two websites where you can watch the news and some other shows in Teochew with Mandarin subtitles: http://ecstv.com (I think it's HK based) http://www.strtv.cn/tv/category/v2.html (from Shantou, I find it easier to understand but the site is so slow you will have to let the video load for quite awhile)

I think there are many ways to do that, to begin is good read a lot of articles in the language that you want to know, listen songs and try to learn its lyrics and the meaning. To me the best way to study is watching videos on Youtube, I think there are nothing better, I think very boring to study grammar and that help me a lot and become easy.