Reading is a good way to expand vocabulary and improve knowledge of Russian. But the result will depend on how actually you are reading.
1) If you translate every unknown word the process of reading will be very slow, boring and as result not effective.
A big quantity of words will be understandable from the context, you shouldn't write all of them in your Dictionary and translate them. You will remember most of them at the subconscious, especially if they are repeated often in the book.
Pay attention on the sense of whole paragraph or sentence. If you can't understand its meaning because of big quantity of new words - only in this way use translator. Don't try to remember words which you'll never need - like archaisms for example, don't waste your time and memory. Learn only useful words.
2) After reading retell yourself what about you just had read. Try to tell it in 3-5 sentences, but try to make them full and correct.
3) Read in Russian every day. The number of pages depends on your Russian level, from 1 page (basic level) to 15 pages (upper intermediate) will be not too hard, but very useful.
4) Enjoy reading in Russian, choose books which are interesting for you, but not too hard, then watch screening of these books, compare them, discuss with your friends or teachers.
And good luck in learning Russian! :)