If you are taking a standardized test you have no choice, but to figure it out in the flow and context of the passage. Other vocab hacks are:
- does the word have a positive or negative connotation?
- do I recognize any roots or word parts that I know the meaning of?
If you are doing your homework or just reading in general you should never go past a word you don't understand. Sometimes you do so and you don't even realize it and a whole number of manifestations could turn on.
I would go here and download a PDF on the "barriers of study:"
As for looking up a word there are many insufficient ways to do that so here are some steps:
Find a good, simple dictionary. Sometimes googling a definition gives a definition where you don't know all the words in the definition and then you're in a word chain. A good online dictionary is collinsdictionary.com/us because it shows how the word is used.
So once you find a good dictionary:
-find the definition that fits
-make up some sentences with the word until you have a clear concept of it
-repeat that for all remaining definitions because on standardized tests especially, when they ask vocab questions that don't usually go with the most popular definition
-you can also look up the origin of the word followed by idioms, synonyms and any usage notes
Hope this helps. From studying this way personally, my reading comprehension shot up (as well as my IQ).