The best way to learn a new language is to immerse yourself in it. Read in the new language, speak in the new language, listen to music in the new language, think in the new language, and do it until it becomes second nature to you. Then, you will master the new language and know it as well as you do your mother tongue.
Often, I get asked how I make time to write everyday, or how I decide on a topic to write everyday. Although it takes me only about an hour to go from inception to hitting publish, it is like Tai Chi. It is not just about the hour that I'm actively doing the task, actively practicing and actively engaging in writing. It is a way of life. All my interactions throughout the day have this as a backdrop when my mind is slowly imbibing and ruminating everything that it comes across.
Be it Yoga, or martial arts, or music, or a dance form, you don't just practice for an hour a day and then forget about it for the rest of the time and still hope to do well in it. That doesn't happen.
During my initial months of learning Salsa, I attended every class and practiced two hours a week, but learnt absolutely nothing. It was only after I started listening to the music more often did I improve.
Learning Spanish was similar.
When you are aiming to do better in something, it isn't enough to put in just a certain amount of time. It is necessary, yes, but it isn't enough. Instead, you need to live it.
You don't do Tai Chi for an hour a day. You do Tai Chi all day.