Be your own worst critic without being too inhibited; high standards are a must, but don't allow yourself to become paralyzed by perfectionism. Have a vision for what it is you're trying to accomplish while being willing to accept criticism. Whether you're into composition, production, or physically playing an instrument, get regular practice. It can take years to get good at what you're doing, so the sooner you start the better. Don't make hoarding equipment or lusting after legendary hardware a higher priority than actually making music. Having a Jupiter-8 or a vintage Gibson guitar isn't necessarily going to make you a better musician and might not even be the best choice for the sound you're going for.
I just make music on and off as a private hobby and am probably not the kind of person you're looking for advice from, though.