Way to enrich your word power through reading.
Take for instance the following extract in which you may come across new words.
Freddie stared after him, aghast. He felt like a clergyman who has found schism in his flock. It was axiom in Donaldson's Dog Joy that its leading rival Peterson Pup Food was a product lacking in many of the essential vitamins and dogs who indulged in it were heading straight for rheumatism, sciatica, anemia and stomach trouble.
While reading a book you are already into a theme and you follow a train of thought. So even if you come across unfamiliar words you may have an idea about the probable meaning of these words. In other words, you can associate words with the themes and the situation in a particular sentence as you read on.
Now in the above example, Freddie had encountered something unpleasant or shocking in the paragraph preceding the extract. Hence he is Aghast which means Horrified, Appalled or Shocked. The next line describes Freddie feeling that there was a Schism in his flock.
Schism means Division In the next sentence you come across the word Axiom which means Motto or Cliché.
But, you may not be always able to associate a word with a theme or a situation and guess its meaning. I mean to say that this hit and trial method cannot be used with the case of all unfamiliar words. Even if you are able to guess the relevant meaning by relating it to the sentence you should make it a point to always refer to the dictionary.
But you will definitely have a head start in your pursuits to enrich your word power by first guessing the meaning of the word through an association or a relationship with the theme (if this approach is applicable to the sentence).