Rich Vocabulary can make you very confident.

-You can provide precise, vivid descriptions; you can speak more fluently and with more confidence; you can understand more of what you read; and you can read more sophisticated texts.

-A good vocabulary can enrich your personal life, help you achieve academic success, and give you an edge over others in the workplace. You can truly gain the proverbial verbal advantage.

-Make the commitment to improve your verbal skills. Success does not come without effort. Understanding the parts of a word gives you clues about its definition, and this can help you when you take tests,write reports, or make speeches.

You should have a dictionary or thesaurus handy as you work with any kind of language activity.

OneLook Dictionary Search
More than 13 years old , with a database of 5 million words..no doubt onelookdictionary is indexed by more than 1024 online dictionaries.You can find,  define and translate words all at this site.A must for every word lovers!
Visuwords
Look up for words to find their meanings and its associations with other words and concepts. Make diagrams reminiscent of a neural net. Learn how words are associated.

Merriam Webster: Visual Dictionary

The Visual Dictionary Online is an interactive dictionary with an innovative approach. From the image to the word and its definition, the Visual Dictionary Online is an all-in-one reference. Search the themes to quickly locate words, or find the meaning of a word by viewing the image it represents. What’s more, the Visual Dictionary Online helps you learn English in a visual and accessible way.

OneLook Reverse Dictionary

OneLook’s reverse dictionary lets you describe a concept and get back a list of words and phrases related to that concept. Your description can be a few words, a sentence, a question, or even just a single word.
Online Spell Checker
Free online spell checker that provides you with quick and accurate results for texts in 28 languages (German, English, Spanish, French, Russian, Italian, Portuguese etc.). An alternative tool: Spelljax.

WordWeb
A one-click English thesaurus and dictionary for Windows that can look up words in almost any program. It works off-line, but can also look up words in web references such as the Wikipedia encyclopedia. Features of the free version include definitions and synonyms, proper nouns, 150 000 root words and 120 000 synonym sets.

Use index cards to create an easy and effective study tool. Put the vocabulary word on one side and its meaning and an example  sentence on the other. You can copy the example  sentence from the word list, but you will learn the word faster and remember it better if you create a sentence of your own.

2.Use the words as you learn them.

The best way to remember what a word means is to use it. Make it an active part of your vocabulary as soon as possible. Use the word in a letter to a friend, as you write in your journal, or in your next conversation with a coworker. Share your new words with your best friend, your siblings, or your spouse.

Games like Scrabble and Mad Libs, for ex , are great ways to improve new vocabulary words.

3. Keep it manageable.

You can’t learn thoudands of  new words overnight, and you will only get frustrated if you try to memorize many words all at once.

4. Review, review, review.

After you learn a set of words, remember to review those words regularly. If you simply keep moving forward with new words without stopping to review everything you have already learned, much of your effort will be in vain. Practice  is the key to mastery, especially with vocabulary. The more you review the words and their meanings and the more you use them, the more quickly and permanently they will become part of your vocabulary.

5.Create or play word games.

Games like Scrabble and Mad Libs,  for ex , are great ways to improve  new vocabulary words.

6.Use Dictionary.

Make it a habit to find a new word every day. Look in the dictionary, sign up for “A Word a Day” (see dictionary.com) or make swapping new words a game with a workmate or fellow student.

7.Speak to people.

You’ll be surprised to see different cultural influences and occupations, all of which will introduce you to new words.

If the English you hear sounds strange, it may be a foreign expression! So pay attention to those words and expand your vocabulary.