Both speaking and writing. And everyday practice is also very important.

Just to add my bit, it depends on what you want to be able to do. figure out what that is exactly and set goals accordingly. if you want to be able to read then you should practice reading, if you want to be able to speak then practice speaking.

It matters what your goals are. If you want to live in an English speaking country or make friends with English speakers, speaking will probably be more important to practice. If you want to have perfect grammar, take proficiency tests, or spend time on English websites, writing will be more worth your time.

I think you must find a smart way to learn foreign language and be hard-working. It's just my opinion.