Translation of sneaky in Spanish

If you want to learn, you need milestones, so that you can plan your learning curve. Together, we will decide on 3-4 days, where we will study intensely. Perhaps your German will get a little bit better by then.
We have learned that some tenses, such as Present Tense are easier and not as complex as others. Is that right? In my opinion, tenses in English are much easier than in the Spanish language.
My family and I live in Frankfurt. I love South American literature, Jewish music, winter sports, and of course the time with my family. What do you do in your spare time? Reading Spanish books too?