"Rawad and Bob"
Listen to Arabic recordings every day while following the letters with your eyes (So you'd need transcripts). Forget the meaning for now, just train your eyes to keep following the letters while noticing the sound being made. You'll find this a bit overwhelming at first, but give it 2 weeks of daily practice (10 minutes per day are enough) and you'll start feeling the benefits. Keep doing this throughout your learning, and the long term benefits will be immense, as you'd be much more familiar with the sounds of the language and its structure (unconsciously) and your brain will be a lot more ready to absorb the information once you get to it in the Duolingo tree (or using any other resource).
If you'd like general tips on learning languages, I recommend you read my previous posts on the subject, which you can find by following these links: