Depends on which language you are learning!
First alphabet
Second simple vocabulary, just the basic to have notions if you will go on holidays or smth like that
Third: Grammar: which includes verbs and sentence structure
Fourth: Typical expressions: it might not be too important, still if you are learning German is one of the main thing you have to lean how to structure sentences, sometimes doesn't work in a portugese (my language and neither in english) and trust me is the worse thing ever.