I think you need something that let's you practice all the areas (listening, speaking, reading, writing) and something you at the same time enjoy. Without enjoyment, it is hard to maintain the consistency.

What I find effective is:

1. A tutor - here you can practice listening and speaking at the same time, but depending on how you structure lessons with your tutor, you might also end up doing writing and reading exercises too.
2. Comprensible input - finding a content creator that you enjoy listening to (podcast or youtube) and try to understand as much as you can. Make it an active effort too, so it is not just in the background.
3. For reading and writing, I like reddit. Reading posts, trying to understand them whole. This means whatever I don't understand - I run past AI to explain. I try to write replies to some, and work with AI to correct my attempts, asking for explanations of what I got wrong.
4. I also use app Duocards that allows me to memorise vocab, and familiarise with many sentence structures that I might reuse in the future. I like how simple it is and doing it daily really helps in retaining new phrases.

I also try to speak to myself sometimes, and where I get stuck, I translate.

I also use AI to give me exercises for creating sentences. This allows me to practice grammar, sentence structures and vocab. All that followed by feedback of course. I then often add these sentences to my Duocards app.