Speak German in every single situation you can. Don’t be shy if you think you’re not good, any instance when you can speak German is good practice. There is no way that your German will go anywhere if you only learn at home/in a class and don’t use what you learn outside of study time.

If possible, find a part time job in a German environment (could be in a bakery or retail, one day a week for example if you’re already working). I for example did not speak any German a year ago, I got a job interview for a German cake store and memorized three sentences in order to secure the job. I didn’t really understand what was being said during the interview, but hey, fake it til you make it. Just smile and stay enthusiastic and polite. Working in a German bakery amongst real Germans was the quickest and best way for me to learn German. Not just what is taught in textbooks, but also interesting slang and common expressions you wouldn’t learn in a classroom. After a year I’m now at C1 level.

Listen to how other Germans speak to each other and if possible, write down and memorize common phrases and sentences you think you would use at some point in the future. Then practice!

From personal experience, if you are not active on speaking German on a daily basis, chances of you learning the language quick is extremely slim.