When starting a new artwork, search for the right size of canvas. Do you want to paint a big or just a small piece. It is the beginning of the entire process. You need to stay focused and experience every step. It will make you loose all negative thoughts and fears. It will bring you a new way of seeing things.
Then decide the brushes and colors. The choice of brushes depend on the mood and the things to paint.
It is not necessary to begin perfectly and know exactly what you want to paint because it will develope and you will figure it out. Keep calm and enjoy.
So start painting & just relax & love the process without fear
Here are some inspirational beginnings of paintings.