The single biggest obstacle to any new learner of German (or even an intermediate or advanced one) is embarrassment. Maybe you'll say the wrong word, or mispronounce an umlaut, or forget when to use Sie and du. But by embracing instead of fearing these mistakes, you can greatly accelerate your learning curve while at the same time actually enjoying the process.
The Perfect is the Enemy of the Good
No one is naturally able to speak an unfamiliar language without practice. Even the most adept polyglots have to spend weeks or months practicing with new phonemes and grammatical structures until they're able to speak and interact comfortably. The challenge for most of us is that those early weeks are incredibly uncomfortable. Often, it's tempting to put off real world speaking practice until you reach an arbitrary level. Maybe you convince yourself that you need to learn a certain number of words, or attend a certain number of lessons, or read a certain number of books.
Instead, accept the fact that you're a beginning, and that no one cares how bad your German is. In fact, most Germans will praise you for even taking the time to learn their language. When you first start, no one expects you to be perfect, so focus on getting to good. Learn a few key phrases and build on those until you can interact in simple conversations.
Don't get Bogged Down in Grammar
German is a gendered language, and der, die, and das have haunted my dreams every since I took my first German class in 6th grade. Combine this with the cases, the strange word order, and the backwards numbers, and the German grammar can become quickly overwhelming to new learners.
This is a shame, because it obscures what is most important about language: Communication. Although it is ultimately important to know the difference between Akkusativ and Dativ, and to know which article goes with Tisch, at the beginning stages of your studies, being able to communicate is much more important than knowing your grammar quizzes.
Knowing How to Say it is Half the Battle
German is very different from English in that it has standardized pronunciation. When I write the word "tear" in English, there's no way to know the meaning of the word without context. It could be the verb synonymous with "rip," or it could be the noun referring to the water that leaks from your eyes. In German, reißen and Träne can only be pronounced one way.
Both words contain several sounds that are difficult for Americans to say ("r" and "ä"), and which require weeks or months of practice. Instead of spending a lot of time pouring over dull textbooks, spend your early days on pronunciation. If you can say Eichhörnchen without any trouble, then you're well on your way.
Don't Waste Time and Money on Boring Textbooks
Some people love grammar and spend their weekends pouring over grammar textbooks. I doubt anyone reading this post is one of these. So take the advice of Benny the Irish Polyglot and stop wasting your time on traditional materials that bore you to tears. Instead of reading tired passages and listening to stilted audio, try watching German soap operas (Verbotene Liebe is my favorite) or setting your Netflix account to run German subtitles. German is a living language, and its important to find learning aids that will give you access to the colloquialisms, slang, and idioms that color everyday speech.