Learn a New Language
How to learn a foreign language is the one million dollar question, but actually there is no magic answer, it is suggested that many aspects should be taken into consideration, as well as some tools used to learn a new language, the good news is that there are methods and techniques that could be used for that purpose.
Listening & Speaking
Vocabulary: You will be amazed to know that normal people use only about 4,000 words as their vocabulary source, even though a language could contain a million words, still only a very small part of it is used in the every day life, which is a good news. Another good and surprising new is that 50% of the words used everyday make only between 100 to 200 words. So my advice to you is that when you memorize words, try to prioritize based on your needs, give priority to words you think you may need in a normal conversations ... A smart way around vocabulary can save you a lot of time and enables you to speed up your learning process. You may want to memorize a number of words everyday, the number would depend on how much time you can dedicate to that and also how fast you want to learn the language. Let's say you decided to memorize 20 words everyday, remember that the more you memorize the harder it gets, once you memorized today's 20 words, tomorrow you will have first to see if you still remember today's vocabulary, then you can add tomorrow's 20 new words, and so on.
Grammar: it's the element that helps you manipulate the vocabulary you already learned. It doesn't make sense to have a car without knowing how to drive it; grammar shows you how to "drive" your vocabulary. How to play with words, which word to place first or last, how to shape a word depending on the situation and needs, also it helps you enrich your vocabulary, and show you tricks that can double the number of words you know just by simply showing you a rule to follow, for example, let's say you learned some words (adjectives) like: natural, historical, exact, proud ... Grammar will tell you that if you add "-ly" to these words you will get an adverb that can work in a whole different situation, that would allow you to use what you already memorized and "create" others words from the original ones such as "naturally, historically, exactly, proudly... this rule could apply to thousands of adjectives, that's a lot of time saved, and that's just one example. This exists in all languages not just English. Grammar will help you shape your vocabulary the way you want, just like clay, you can make different shapes out of one piece of soft clay, and so can you with one word.
Writing: now you reached the part where you can combine vocabulary and grammar, and putting what you learned into practice. For example you let's say you have memorized the German words: Freund, aus, Deutschland, and you learned in grammar how to use the possessive (mein/e, dein/e, sein/e...) also how to use the verb (kommen: komme, kommst, kommt...), that will help you write a sentence like: mein Freund Gerhard kommt aus Deutschland (my friend Gerhard is from Germany).
Basically writing is your first practice of what you have learned from vocabulary and grammar. There are many ways you can write and learn at the same time, chatting or writing letters to penpals is a good way to start.
Listening & Speaking: when listening you're the "receiver", so always pay attention to "what" is said and "how" it's said. Because before speaking you need to know how things are pronounced, if you're a new learner it may seem that the speaker is speaking very fast, the more you improve the more your ears get adjusted, because your brain will be processing the words at a faster pace due to some experience you gained. And since you're the receiver you will be able to learn new things that you can add to your vocabulary list as well as to your grammar.
Speaking is just like writing; the one difference is that you need to use your mouth instead of your pen. This will test all what you learned (vocabulary, grammar, writing and listening), it takes more effort and your brain works harder because in addition to "putting all your skills into practice" you will have to do that way faster. When you write you have enough time to write ideas and see if they're well organized, check for errors, change ideas ... but you don't have that comfort when you speak, Speaking is more straightforward. The good news is that after enough practice, speaking will become natural, almost like your native language, you will be using some efforts but subconsciously, and maybe speaking will become the easiest thing to do.
Memory: Since vocabulary occupies a large place in every language, it can make or break your learner quest, vocabulary is often a matter of associating a meaningless collection of syllables with a word in your own language. Usually people associate these words by repetition or by saying the word in their own language and the foreign language many times over. You can improve on this tedious way of learning by using for example the following technique:
Mnemonics to link words, this method is based on using images to link a word in your own language with a word in a foreign language. For example, if you're learning Spanish, and learned that bread in Spanish is "el pan", to make it easy to memorize this new word, imagine bread on a frying "pan", which will help you one connect one thing to another in case you forgot. This is called the LinkWord technique, it can speed up your memorization efficiency and therefore save you a lot of time, but you have to be creative and make a good association that you may not forget.
Practice: it's what keeps you in the right path, first because it allows you to "play" with what you already know, and discover what you don't know, also it helps you learn new things and best of all it prevent you from forgetting what you already learned. Practice lets you know your level, and by knowing your actual level you can determine you're your next level would be.
Motivation: it's what keeps you going, and that's something you really need more than anything, because many language learners lose interest within the first stages of their learning quest, that will not only mean that there will be no improvement, but also may put everything you learned before at risk, because lack of motivation leads to lack of practice, and gradually you will forget most of what you know.