Use a dictionary.

First of all you need to familiarize with basic words when you are starting to learn, don't get crazy and always carry a dictionary with you, could be a pocket dictionary, an app in your cell phone (it's very useful an easier to use it) or an online dictionary in which you access online and it's similar with the app.

Look the word up in the dictionary and try to understand how it fix with the context you have. I recommend you to do a list in which you could put all the new words in order to review it, in the case that you forget it. I prefer online dictionaries because sometimes it's easy to understand if you have an example, such as a phrase and in this case dictionaries apps have it, also with the pronunciation.

There are multiple choices if you want to use a dictionary to learn English base on what you want to learn. For kids a nice tool is the picture dictionary, the oxford junior dictionary which are illustrated to have a better idea on what the thing is. There are dictionaries also base on verbs patterns, idioms, only for pronunciation or abbreviations, etc.

Here is a explanation about How to use a dictionary, so click on it a start to learn.

Then some links for online dictionaries:

http://dictionary.cambridge.org/
http://www.wordreference.com/definition/
http://www.merriam-webster.com/