Vocabulary is one of the most important parts of learning a language. An archer is nothing without any arrows. In the same way, without a good set of vocabulary at your disposal, grammar knowledge won't help you much. Vocabulary drills should be an everyday activity if you are really serious about learning Korean. This everyday repetition will help get the words in your head so that you can use them when you need them.
Memrise - This is a website where anybody can make language learning games (classes) to help you learn vocabulary. Every "class" can be different since they are created by different people. Classes teach you through a fun game-like quizzing method based on the concept of spaced repetition to make your learning experience faster and more efficient. Here is a link to their FAQ section if you have more questions!
Anki - Anki is similar to Memrise in that they utilize the spaced repetition method to strengthen memory and assist you in learning better. They have a website where you can learn more, a desktop client you can use on your computer, and apps for iPhone and Android phone users. As you study vocabulary with Anki, you mark each word as either "easy," "medium," or "hard." As you do this, the app remembers which words are hard and easy for you and drills you more on the hard words and less on the easy ones. This helps you to maximize your vocab study time!
Simply copying down pages out of the dictionary may seem like a good idea, but in reality it will hurt you later one. Knowing a whole bunch of unusable vocabulary is like studying the wrong chapter for a test. Yes, you have learned a lot, but if its not the information that you actually need to use in real life, it is only going to fade and prove useless later on. So with that being said, its really important that you get good, usable and relevant vocabulary to the situations in which you will be using Korean. For more on this, check out the vocabulary tips in our blog.
TalkToMeInKorean.com - This is definitely one of the most comprehensive resources on the web for learning Korean. In terms of vocabulary there are a lot of ways to use TTMIK, as it's called, to collect vocabulary. One way is to use their "Vocabulary Booster" lessons that give you vocabulary based on a certain topic. For example, body parts! Another way is to simply go through their grammar lessons and study the vocabulary in the examples they use.
HowToStudyKorean.com - On this website, you can study by following the grammar based lessons from Unit 1 to Unit 5, with 108 lessons in total. Each lesson has a set of vocabulary words that go with the lesson. You can enter these words into Anki if you want and use that as your vocabulary drilling method.
FreshKorean.com - This is a very simple and easy way to pick up vocabulary. Fresh Korean has a bunch of different images and lessons that contain what we'll call "batches" of vocabulary words. These are words that are usually related to each other by topic or situation in which they can be used. Here's an example of one that will give you vocabulary words about different occupations.
Some useful links to Korean <-> English dictionaries:
Verb Conjugation Dictionary - This is a very useful tool if you are still getting used to conjugating verbs. Also, it can be helpful to check how irregular verbs are conjugated.
Hanja Dictionary - This one can be very useful for intermediate to advanced vocabulary learning as it will help you to create a mental network of words and their connections through similar Hanja. For more about how to use Hanja to learn Korean words, here are some videos.
Naver Dictionary - Probably the most used dictionary with a variety of different sections.
Daum Dictionary - Functionally, this is almost the same as Naver dictionary. Different people may have different preferences as to layout, structure, etc.