Thanks for the reply! I ment that I've understood that there are two different ways to conjugate a verb, 1st Е-conjugation and 2nd и-conjugation. And in this way, спатъ is 2nd conjugation, because it's ты спишь, он спит etc and not ты спаешь, он шпает. Am I right? My question is, that is there any rule, that it's conjugated this way and not the other?
Ahah! Now I get it. Thanks for taking the time and explaining this. Well, there are always better ways to learn grammar. Whenever you feel like you're lost, then know that your teacher isn't good at explaining it. I learnt verb conjugations from Michel Thomas's audio CDs. That is IMHO the best method to start learning Russian. Duolingo on the other hand is perfect for learning declensions. Back to your question, a very useful book named "555 Russian verbs", verb no. 466, explains it like this: спать/поспать to sleep stem: irreg./irreg. regular type 2 verb (like говорить)
Okay, I hoped there's any rule for that, but if irregular, then irregular.. :D Thank you for the reply and recommendations, I like the declensions part as well at the moment, but already see, that I should start working on conjugations and other grammar rules with some other source as well.
Иногда я говорю по-русски seems fine. Sometimes you do this, sometimes you do that.. works the same as "sometimes" in English: start your sentences with it, use it as much as like, and have fun with it. To get you more comfortable with the word, listen to this song: https://www.youtube.com/watch?v=7Wy3p1JSK4s