It takes immense practice, and I've found focusing on quiet music helps. It also helps if you like to practice Wake Induced Lucid Dreaming. You just ease into any thoughts that might come across.

The way I learned meditation is you're not going to be rid of every single thought, so instead focus on sounds, focus on your breathin, be nice to yourself if a thougt does occur, and then try to focus back onto nothingness/w.e works for you.

30 minutes a day has really helped me feel more in control, when I can remember atleast.