You learn a language by using it because you need it. The formula is Need + Use = Learn.
Most people follow the formula Want + Study = Learn. That's like trying to use a book to learn how to ride a bike.
All "learning" a language means is being able to use the language in the situations you need to use it in. So focus on learning to speak one topic or situation at a time. But again if you're not actually using the language it doesn't matter.
The next thing after choosing a topic is knowing what verb you need to speak on that topic. For example, if the topic is 'Spanish', the verb might be 'I speak', or 'I'm learning'.
The verb you choose will flow into vocabulary like branches. 'I speak...English; a little Spanish', and so on. Look at any one of my Language Matrix lessons to see how to plot this on a 3-column page.
Learn your highest frequency topics, and highest frequency verbs. The latter is available in several of languages for free here: http://www.tonymarshmethod.com/beginner-kits/
Practice writing and speaking. That's output.
The more beginner you are, the more output you need. For example, if I know zero words in a language, it doesn't help me very much to turn on the TV and listen to that language spoken. I need output. I need to begin conversing in that language using what I know of topics, verbs, and vocabulary. (The importance of your output being in the form of actual conversation is that you are also getting input from the other person.)
As you progress, input becomes more and more helpful (it's always helpful, it just becomes more and more helpful as you go and you want to get to the point where it's helpful as soon as possible, which you do through using the language as described above).
When it comes to listening strategy, follow these steps:
1. Establish context.
2. Listen for keywords.
3. Get the main idea.
Step 1. can often make the difference between understanding someone 100% and understanding them 0%. When you know generally what someone is talking about, it's easy to fill in the blanks by just listening for their keywords.
Getting good at guessing is the main skill here. And by the way, you establish context by asking questions. So if you ask someone, What do you think about xyz? there's a better chance you'll get the main idea of their answer than if they had volunteered the same information to you without your having asked. Plus, at that point you'll be able to apply the other most important skill in listening strategy, which is to imitate.
The more questions you ask, the more you learn.
To summarize, prepare yourself for output by learning your highest frequency topics, one topic at a time, by mixing and matching verbs and vocabulary. Practice writing, then go out (or online) and use the language.
Create conversation by asking questions, and practice applying the steps of listening strategy.
The goal at the beginning is to reach the point where you have enough experience in the language (both output and input) that you learn automatically -- like a snowball that's heavy enough to roll by itself. At that point language is an afterthought (as your native language is), and you're just living.