First of all, you have to have a source for vocabulary Spanish websites, newspapers and magazines can give you tons of new words and phrases to use, so that's a great start, and you'll get even more. I also suggest getting a dictionary; this will obviously help when you need to translate an idea from your language, or have heard a new word in Spanish that you don't know, and want to look it up. If you have already found a good dictionary and are using it, that is great. Keep it up.
Now, the next step is to consider getting your hands on a Spanish-Spanish dictionary, rather than a translation one. You have enough of a base vocabulary now that you can start to use the same dictionary that a Spanish speaker would use. Don't go get a big doorstop of a dictionary at first; try to get a student one, and remember that a Spanish picture dictionary is an easy way to start. You will probably want to hang on to your translation one for a while, but try using a Spanish-Spanish one now too. Es mas autentico, and is a great way to challenge yourself to increase your vocabulary.
So, there you have it; awesome resources to find much of the vocabulary that you will need to speak Spanish like a native (with a nice little accent). But, what techniques should you use to learn quickly and effectively? Well, your best learning styles, of course:
Are you a visual learner? Flash cards are an excellent way to learn and remember your vocabulary words. Challenge yourself to read a Spanish newspaper in your free time, or keep it in your bag or car to take out and read when you have time. This type of constant, repeated input is great for visual learners.
Are you an audio learner? No problema; try getting hold of some Spanish music onto your MP3 player and listen to it as you work, work out, or drive along in your car.
Are you more of a kin aesthetic learner? Well, your teachers probably knew what was best for you; writing lines! This means writing vocabulary lists, with translations, perhaps putting down each word three times. The movement involved in reading and writing, and repeating this action, is a very good way for learners like you to remember information.
And a fabuloso way to learn vocabulary for all types of learners, in a first or second language? Read! Seeing the vocabulary being used within a context and it in its different forms is a very real way to approach it and you will learn even more by doing this.
Of course, you can also find Spanish articles, books and information written about topics you enjoy, too, and this is a great way to use your own motivation to help you practice. As I mentioned before, children's books are also excelente, because they are simple, and often are stories that you know. So many possibilities!
And lastly, of course the very best way to learn vocabulary is to combine all of your senses, use every learning style, and use your Spanish. Use it to speak to others, listen to others, sing along with others or write to others. Using Spanish in real situations will naturally increase your word power, and enjoyment. And that is what it's all about!
Tip: Have you tried watching television yet, to help you improve your listening, vocabulary and general understanding of Spanish? Try telenovas. These are Spanish soap operas, and are very popular throughout the Spanish speaking world. The language is usually pretty simple, and it's a fun way to increase understanding. You can find some on most cable networks.