To become an advanced witch, you also need to be able to concentrate. To become better at this, you can sit in a room and focus on one thing and don't think about anything else, until you're done. It can be a sound, picture, object, etc. The first time, do it for 5 minutes, then the next time for 7. Keep increasing the time, until you can do it for 30 minutes, or even an hour.
The last and most important thing is to PRACTICE. If you don't practice, you'll never get any better.
Thank you for reading and I hope you all will become better witches! :)