Practise makes perfect, according to the old saying. So the best thing to do is to get started, as soon as possible.

If you're a total beginner, I don't think that trying to watch a whole film in German at first or attempt a conversation with a native would be the best way, but try to introduce German in your routine, listening to songs, maybe changing the language of your phone, trying to make some exercises everyday or reading something (even if you need to translate).

I don't know if you already have something to study or not, so I am going to share some of the tips I've already shared with other learners:

1 - Nicos Weg by Deutsche Welle, available at https://learngerman.dw.com/en/beginners/c-36519789

Completely free. You watch a short video and make some exercises everyday (or according to your schedule). There are activities from level A1 to B2. There are many other activities on Deutsche Welle's website, but this one is very interactive and you can start from the basics.

2- Assimil

You have to pay for it. Available at bookshops. It's a method you study everyday and you listen to audios, read texts and make some exercises to get you used to German structures and grammar in a gradual way

3 - Pimsleur

You have to pay for it. Available at bookshops. Mainly focused on speaking, you learn some new words everyday and you have to interact with the audio. It's a good way to start talking when you're still not confident enough  to do it with a native speaker

Most of those methods I recommended require about 30 minutes a day, but you can combine them. Of course you can use something else that works for you, but I think the important thing is trying to have fun instead of just memorising stuff, so that you keep yourself motivated.

Good luck!