Improve my Cantonese, 中文, and Chinese

I learned to speak Cantonese and write 中文 before i began to learn English from television and in kindergarten. Then i lost interest. In college i studied a semester of Chinese, where i realized i could better use my time improving my Cantonese, then levering it to learn 中文 and in turn levering it to speak Mandarin. I need to find capable software, perhaps a class, and get to it.