The importance of movies and more
I feel that movies, video games, music, etc. are extremely important to language learning. If you finish a skill tree of any language, you still won't be able to use it that well in conversations. Movies and music help get you used to the sound (and speed) of the language. Another very helpful thing is playing video games or chat rooms. I do both and it's super fun, I love it. All these things are fun, and yet help you learn a language (like duolingo)! Just search google for "(your target language) chat room" but get a translator ready!
Challenge: Try setting your phone, facebook, etc. in your target language!
I agree! Duolingo is great for reading and writing, but has limitations in the practical realm. There are a lot of great websites with Spanish TV to put your training into practice. The website edustation also has the words along with the dialogue to help you follow if they are talking too fast. You can learn a lot of interesting things meanwhile.
I consider DuoLingo a springboard: once you've completed the skill tree, you'll have no trouble reading a language, but in order to use it effectively in a conversation, you need a lot of real-life practice.
Fortunately, I've discovered an awesome way to improve my verbal language skills: I look for "Let's Play" lists on YouTube. These are play-lists of people simply playing a video game and putting the entire thing on-line for all to see. Since many Spanish and German games are dubbed, you have a fun way to learn what proper pronunciation sounds like.
Yep, it's amazing how many fun options there are. I play minecraft on a spanish server (IP is 184.108.40.206:25580 for whoever wants it) and it's not difficult to communicate, but I always have a translator ready. And I also use a English/Spanish chat room, espanglish.com. What I'm working on now is getting more audio input, like music. One of my favorite Spanish artists is Quique González.
I have actually started changing some of my personal things into German and it has been a lot of fun. I downloaded a German keyboard format for my computer and one for my phone and I also use the words randomly at work and with friends. And it's great when I say something and someone asks "what does that mean" because it helps me reaffirm that I actually know what I am saying. I'm not quite ready to put my phone in German but I hope to do it soon.
You actually don't have to switch your keyboard to German layout as many keys other than the letters will be hard to find: I used the Microsoft Keyboard Layout Creator: http://msdn.microsoft.com/de-de/goglobal/bb964665.aspx to create my own layout. Just took the German one (my native) and put special characters that I need for French, Spanish and Scandinavian languages under the key's Alt. So when I need an "ñ" I just type Alt+n. You could make Alt+s turn to "ß" easily with this tool or Alt+o to "ö".