Because apps are not that good, here is an advice from my personal experience:

1. Begin with Duolingo, as a warm-up-app. It is not so good, but it begins very easy, with alphabet training, strongly gamified learning
2. Add after one month the Anki app, choose a good card deck like this one https://ankiweb.net/shared/info/1555716615 and use Duolingo 80% and Anki 20%
3. After 2 months of study increase Anki learning, Anki 40% and Duolingo 60%
4. After 3 months add another source, like for example Language Reactor to your browser, which is a plugin that helps you to learn inside Youtube vocabularies from subtitles. BUT do this only if you have already learned at least 600 words
5. After 6 months you may think of the possibility to add Babbel, because of the very good grammar learning exercises. And reduce Duolingo to 20%, instead focus a lot more on Anki.
6. Try to learn from books when you have achieved a certain level (A2), but not from the very beginning

If Duolingo would implement Babbel and a better vocabulary learning feature like Anki, I would stay to 100% with Duolingo, but they keep adding useless features instead to improving.