There are a number of strategies you can use to work out the meanings of new/unknown words which will help with your overall reading comprehension. Click here to study these strategies.
The ability to guess meaning from context is a useful skill to practise and try to improve. The things which will help you work out the meaning of an unfamiliar word are:
a) the meaning of the text which surrounds it;
b) the way the word is formed;
c) your own background knowledge of the subject.
Most words may have several meanings/nuances depending on the context and many of them may serve different functions in the sentence. If you still feel you can’t understand the new word, look it up in a dictionary.
Guessing is useful only when you can interpret/understand the surrounding text. If you think you have exhausted the contextual information available to guess at the word, LOOK IT UP IN A DICTIONARY. No matter how good your English is, you will never fail to come across unknown words in nearly every text you’ll be exposed to.
Inferring and guessing meanings of unfamiliar words is, thus, a strategy which is worth developing in your learning process particularly in those situations when there is no dictionary available.
I highly recommend you to go to this website and have the opportunity to revise guessing meaning from context strategies and practise.