I learned Spanish very quickly and was able to communicate effectively.  Native speakers would tell me that I sound like Spanish is my first language.  I was able to think in Spanish and understand in Spanish.  I was eating and breathing Spanish.

The few years in High School Really Helps.

When I decided to really study Spanish, I purchased Rosetta Stone and started going through the program.  It was very easy to start and was much more fun than reading a book or finding courses online.  I noticed that almost everything I learned in high-school started coming back to me.  It is like my brain held on to it and needed exercise to come back.  Once I learned a few phrases, my memory power increased and I was memorizing more and more words and phrases each day.

Learning Phrases instead of Words.

It is very boring to just sit down and memorize vocabulary words.  That type of rote memorization decreases excitement.  One helpful tool is to find a book or magazine written in both languages. Read the one in English and become familiar with its contents.  Then memorize line by line the sentences in Spanish and English.  The English part will be easy and the Spanish part will be just meaningless sounds at first.  After you have a good handle on the phrases, research the meaning of each word.  You will see that many words mean something slightly different when you translate them individually.  In this way, you learn the way people write or communicate in Spanish instead of just learning word definitions.  This way is also much more enjoyable because you can see progress faster as you memorize full thoughts instead of random words.

Pronunciation is Key.

While listening to other native English speakers try to communicate in Spanish to native Spanish speakers I noticed that the English speaker usually had the vocabulary and phrases correct, but the native Spanish speaker could not understand because of Pronunciation.  Once I learned basic phrases and continued to memorize sentences, I listened to the way Native speakers spoke those same words.  You can download audio books in Spanish or use the pronunciation function in Rosetta Stone to help you with this.  Focus and concentrate on the rhythm and inflections as native Spanish speakers express their thoughts.  Try and try again to mimic their facial expressions and tongue movements.  This is Key!  If you can say a few sentences perfectly, then you will get more excited when others understand and you will be more motivated to continue learning.

Get obsessed.

If you are breathing and eating spanish words all day, you will learn much faster.  If you always have it in your mind that you are trying to learn Spanish, you will begin to think about words to use in every situation.  Have a dictionary handy and capture some words in your mind.  Remember that a language is form of communication, it's not a subject like math or science, its broader than that.  Think about it all the time.

Rosetta Stone worked for me.  I went through the software program a while back and then sought native speaking friends to practice with.  I was a bit embarrassed at first but I learned to find children to practice with first.  They are less intimidating and will always correct you.  Sometimes adults get embarrassed and will not correct you when you make a mistake. 

Keep and open mind and have fun.