If you're a straight guy, learning Japanese from a female is dangerous. Certain phrases are specific to females. A grateful woman would say "Domo arigato gozaimashita." - Thank you very much. A man in the same situation would grunt out a "Domo" or, if speaking to a male superior, a clipped "Arigato". If you learn from a girl, you will speak like one and your male Japanese friends will laugh at you, call you Pajama Boy, and make you pour them beers all night. Or so I've heard.
I rode a motorcycle for the four years when I was stationed at Yakota. I learned Japanese nouns and verbs based on what I needed to interpret a map, get directions, find food, or a place to camp. The other thing I did was to coach English as a second language to Japanese kids at an English Academy. I marginally improved my grammar by having them translate English phrases from their texts. Give and take.
Japanese is difficult only because it is not really as complex as English or latin-rooted languages. For most verbs there is only one tense. And if you want to ask a question just add a 'ka' on the end of the verb.
I have met very few Americans that are fluent in Japanese unless it was spoken in their childhood homes.
Good luck with it.
