Thats a wide topic and there are different ways to achieve invisible cuts.
) You can search vor "in camera transitions" and practice them. Some of them are easy and have a big impact on how the video looks.
) Try to have continuous movements either camera or on screen.
) It's important to guess where the viewers eyes are on the screen. It looks a loot smoother if you don't have to jump around on the screen. For example: If you have an actor walking from the left side of the screen to the right, the eyes of the viewers will most likely be on the right side of the screen at the end. In the next scene you should have the main thing also at that side.
) Plan your shots and have the edit in mind when shooting. Sometimes it helps to pick the music first, then think about the transitions and then start to shoot. Most of us do it the other way round.
) Look for good short films on YouTube, watch them frame by frame and then try to imitate the cuts. I would recommend the videos from JR Ali or Brandon Li. Sometimes you even find tutorials on how they made specific transitions.
) Don't forget the audio. L and J Cuts or sound effects are supporting the flow.
The most important thing is to watch videos and movies from an editors point of view. Try to see how and why they cut on specific points. Then think about what you can use for your own videos.
But here we talk about the art of editing. It's much more subtle than color grading or music choice. Small things make a huge difference and that's why it is so difficult.