There is an old joke about a man on the street in New York City who asks a stranger: “How do I get to Carnegie Hall?” The stranger answers: “Practice.” As old (and corny) as this joke is, there’s a crucial truth contained in it. Your success playing in a group will depend on your musical skills, talents, and abilities. The best way to develop all these is through daily practice.
Let’s get more specific. I don’t mean to say you should practice a lot. You can waste a lot of time with practicing the wrong things. Of course, the basics of technique, music theory as it pertains to your instrument, and perhaps reading and improvising deserve rigorous attention.
It helps to have a good Teacher or program of study to accelerate your learning and avoid pitfalls. You don’t need to spend hours every day to make meaningful progress. What’s most important is that you should be practicing the right things.
Malcolm Gladwell, in his excellent book Outliers: The Story Of Success (Little, Brown and Co., 2008) explains the “10,000 Hours” theory, using the Beatles as an example. The core of this idea is that it takes that long doing something to master it. Applying this to our topic, I would say—beyond the basics—you should be practicing what you want to be the best at.
If you want to be a great soloist, you should be spending time every day soloing and jamming. If you want to write songs, you should be writing every single day. Put your most focused practicing efforts into whatever you want to excel at. You will need to do it a lot if you want to be really good at it. To be good at playing in a group, you need to spend a lot of time playing in a group.
The bottom line is that you need to put in the time to improve your skills and build on your talents. There really aren’t any shortcuts for this part of becoming a great musician. The work you put in is at least as important as any natural talent you may be lucky to have.