The ruling about word stress is complicated and somehow useless to master because like gokuyum said you really learn only by communicating. But I will share with you the four rules I remember and find useful:

1. In general, in Turkish words the word stress is on the last syllable. But if you fail to put it there you are still understood because the pronounciation of letters is the same in stressed and unstressed syllables 

kitap  kitaplık  kitaplıklar  kitaplıklarım  kitaplıklarımız  kitaplıklarımızdan

2. The word stress is always on the syllable that precedes the negation marking MA. This is very handy and helps you to elaborate the verb forms quickly.

                      uyuyámadım 

3. The word stress is on the syllable preceding the progressive marking YOR. Unless that particular syllable has the negation marking. In that case rule no. 2 is applied.

                      sevíyorum

                      sévmiyorum 

4. Also never place the word stress on suffixes like -le, -ken and the suffixed forms of the verb ´to be´.