can you guys suggest me tips to memorize vocabulary more quickly, firmly and effectively??

I find that I remember vocabulary better when I really have an immediate reason to know it. Like, I have to go buy something in that language, so I actually need the words. So putting yourself in situations where you really NEED to use the vocabulary will help you remember it. 

Also, having a simple vocabulary notebook is super helpful, somewhere to collect all those new words, organize them, and review them from time to time. 

And then you can also go to  http://ankisrs.net/ , download the Anki program (it's free!), and make your own flashcard deck, which is fantastic. Especially if you have a smartphone so you can carry it all in your pocket.

I'm with Rob indeed coz I've experienced it and thorouly works.

good luck