To be able to work with things requires certain level of knowledge. You need to understand the things well enough that you yourself know how they work. You have probably started from the basics and worked up from there deepening your knowledge and forming your own understanding.
You might know how things work and how to use them but transferring that knowledge to others is another things. For that, you need to really understand them. You need to know where you come from and how you got there.
In essence, you need to be at least one level higher in your understanding than what you are teaching. I don't think it's possible to transfer your exact level of knowledge. You can just help others get started and guide them through the path you have taken. For the final level, you can only give them the tools and direction they must follow to reach your level.
So to give any practical teaching you need to push yourself even further. And that is a great motivation to learn. If you want to know something really well, try teaching it to others. You might take some things as granted, but when you have to explain those concepts to others you might notice you don't really understand them.