Duko:I memorize song texts. This way I can sing along . It did help me memorize some words & usual expressions.

It is a good idea but songs normally have abnormal word patterns because of their artistic nature.

I can only second the advice not to do rote memorisation of texts. Unless you actually have a strong understanding of the grammatical/syntactical concepts involved to begin with, you're not going to gain much from memorisation. "Garbage in, garbage out". A better idea might be to methodically go through a well-written text and make sure you understand every word and its role in the broader sentence - why do we use an infinitive here, why don't we use the accusative here.