I think there is only one way - it's increasing vocabulary that u will be able to recognise words. For ex in a text I can read the words which I knew already and others - I m not sure. 

I realize there was an English mistake in lmy question. I meant : WILL practising and improving my grammar make it easier..."

Anyway, thanks for the advice heisenbergdndamine.

As for Misslinda, yes you seem to be an analytical person, this is really an original way to look at languages. Enchanté madame !

I think you have to read a lot, and it's better if you read aloud and have someone to correct you. Sometimes there are words that are written in the same way but have different pronunciation depending on the vowels. So, you have to care about meaning and pronunciation. 

Thanks Ziyana. So, really, it is a matter of "recognizing" the words, right ? There is no trick to guess which vowel sound is coming then !

Those "vowel signs" in Arabic (or Hebrew) are called for linguistics as "Letters of God" because no one can guess how they'll be prounounced unless he understands what he's reading.. So there' nothing to do but keep reading, practice makes perfect !

Even people who speaks arabic as their mother language face the same problem, because it's not about your level in Arabic, but about how much you read.. The more you read the more you'll get familiar with words and their correct pronunciation (concerning vowel signs)